One player from every MLB team who is most critical to his team's success
Mark J. Rebilas-USA TODAY Sports

One player from every MLB team who is most critical to his team's success

Spring training is currently in full swing, and believe it or not we are just three weeks from the start of the 2021 baseball season. As we begin to think about which clubs will be contenders this year — and which will be pretenders — let's take a peek at the player on each team who is most important to its chances.

 
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New York Yankees: Corey Kluber

New York Yankees: Corey Kluber
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The Bombers are going to be good. But just how good they'll be will in large part depend on if Corey Kluber can reestablish himself as an upper-echelon starter. The two-time Cy Young winner was arguably the top pitcher in the American League for a half-decade while he was in Cleveland, but injuries have prevented him from being that level of hurler since 2018. The Yankees took a potentially worthwhile gamble by bringing him in this winter. What exactly they get from him, in a rotation that is not deep behind Gerrit Cole, will arguably be the most important thing to keep an eye on with this team in '21. 

 
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Boston Red Sox: Hunter Renfroe

Boston Red Sox: Hunter Renfroe
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Boston has a really strong offensive core with Xander Bogaerts, Rafael Devers, J.D. Martinez, and Christian Vazquez, but they'll need contributions from other places if they're going to bounce back from a disappointing 24-36 record in 2020. They signed right-handed hitting corner outfielder Hunter Renfroe in December, and while the veteran slashed an abysmal .156/.252/.393 as a Ray a year ago, that wasn't what attracted the Red Sox attention. Between '17-'19 Renfroe blasted 85 home runs, and even if he isn't hitting for a high average that power can be game-changing. 

 
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Tampa Bay Rays: Chris Archer

Tampa Bay Rays: Chris Archer
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The Rays traded their ace starting pitcher at the time, Chris Archer, to the Pirates midway through the 2018 season in a deal that quickly became an absolute steal for Tampa Bay. They brought both outfielder Austin Meadows and pitcher Tyler Glasnow south in the deal, and the duo has quickly become important core pieces of a team that just won the American League pennant last season. Archer meanwhile completely fell apart in a year and a half with the Pirates, before missing all of 2020 recovering from thoracic outlet syndrome surgery. Now the trade has come full circle. The Rays signed Archer as a free-agent last month, and they're hoping bringing him back to a place he enjoyed so much success will help offset the losses of Blake Snell and Charlie Morton

 
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Toronto Blue Jays: Robbie Ray

Toronto Blue Jays: Robbie Ray
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The Blue Jays have been a team to buy stock in for a long time, and this season could well be when all of the efforts of their front office really begin to resonate. This team has an absolutely stacked line-up that was bolstered by the additions of Marcus Semien and George Springer, and possesses a bullpen that is now led by Kirby Yates, who in the last normal MLB season was the best reliever in the sport. Notice I haven't mentioned the rotation yet? Hyun Jin Ryu is a solid enough staff leader, but after that lies the issue that could hold Toronto back. Tanner Roark and Steven Matz may be able to survive as back of the rotation arms, but for this team to be good southpaw Robbie Ray has to turn back the clock. In 2017 the veteran delivered a 2.89 ERA in 28 starts for Arizona and even made the all-star team, but he hasn't been close to that guy since. 

 
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Baltimore Orioles: Ryan Mountcastle

Baltimore Orioles: Ryan Mountcastle
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It's going to be an uphill battle for the Orioles to compete in 2021, but if they are in a race in the summer they'll undoubtedly be getting a monster season from first baseman Ryan Mountcastle. The big right-handed slugger debuted last August and swung the bat well in a small sample size, slashing .333/.386/.492 with five homers and 23 RBI in 126 at-bats. Mountcastle was an absolute force offensively in Baltimore's system but was held back mostly by the incredibly overpriced contract of fellow first baseman Chris Davis. Davis is still here, but this job belongs to Mountcastle, and the O's hope he can really announce himself to the Major Leagues this year. 

 
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Minnesota Twins: Alex Kirilloff

Minnesota Twins: Alex Kirilloff
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Young Alex Kirilloff had been the top prospect in the Minnesota system for some time, and last October he became just the 3rd Major Leaguer to make his big league debut in a postseason game. Being added to the roster in last year's playoffs essentially takes service time considerations out of the picture this spring, and it would be stunning if he weren't in left field for this team on opening day. In his only full healthy minor league season, Kirilloff slashed .348/.392/.578 with 20 homers, 101 RBI, 44 doubles, and seven triples, and Minnesota has high expectations for their future star. 

 
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Chicago White Sox: Dylan Cease

Chicago White Sox: Dylan Cease
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The Chi-Sox are another team with high expectations for 2021, and it is not a stretch to imagine them competing for the American League pennant later this fall. Offensively they are brimming with talent, and Lucas Giolito, Lance Lynn, and Dallas Keuchel are quite a top three in their rotation. Their #4 starter, Dylan Cease, is someone who could potentially really take this team to the next level. The young righty completely dominated multiple minor league levels before struggling in his first cup of coffee late in '19, but he showed significant improvement a year ago. In 12 starts Cease lowered his ERA from 5.79 to 4.01, while holding opponents to just a .234 batting average. The 25-year-old should feel comfortable as he belongs in the big leagues now, and he's someone I can really see taking off in the coming weeks and months. 

 
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Cleveland Indians: James Karinchak

Cleveland Indians: James Karinchak
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The Indians are in a transitional phase after trading their best player (Francisco Lindor) and 2nd best pitcher (Carlos Carrasco) to the Mets in January. And for any team that faces an uphill battle in their hopes to seriously compete, their closer takes on immense importance. Teams like these simply cannot afford to give up games that they've already all but won, and for that reason, young James Karinchak will be arguably the most important Cleveland player in '21. In 32 career big league games to date the right-hander has been lights out, working to 2.51 ERA with a 1.05 WHIP, while holding opposing hitters to a .157 batting average and striking out nearly two batters/inning. He only has one save on his ledger though, so it remains to be seen how he'll take to the role, but Cleveland is confident he has the personality for the job. 

 
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Kansas City Royals: Andrew Benintendi

Kansas City Royals: Andrew Benintendi
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Kansas City is a popular sleeper team right now, but if they are going to have success surprising people they're going to need a big first campaign in Missouri from the new arrival, Andrew Benintendi. The Royals acquired the long-time Boston outfielder in a three-way trade over the winter, and they're anxious to see what his left-handed bat can do for their line-up. Before missing most of 2020 due to a strained rib cage, Benintendi was a force for the Red Sox. From '17-'19 he hit 49 homers, drove in 245 runs, doubled 107 times, and maintained both a strong batting average and OBP all three seasons. 

 
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Detroit Tigers: Nomar Mazara

Detroit Tigers: Nomar Mazara
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Mazara looked like a rising star when he launched 20 homers back to back to back seasons for the Rangers, and in '17 he even drove in 101 runs. But the left-handed swinging outfielder watched his production completely fall off a cliff after joining the White Sox for the truncated 2020 campaign. In 136 at-bats the 25-year-old hit just .228 with only ONE home run, and his playing time decreased as the season wore on. Now with a Detroit time that carries minimal expectations, it will be interesting to see if Mazara can relax a little and let his talent take over. 

 
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Los Angeles Angels of Anaheim: Jose Quintana

Los Angeles Angels of Anaheim: Jose Quintana
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The Halos have wasted so much of Mike Trout's career primarily due to poor production on the mound, and while they were in on virtually every big-name starting pitcher this winter, they were unable to lure any of them to southern California. Dylan Bundy and Andrew Heaney are both still here and respectable middle-of-the-rotation pieces, but if this team is going to snap their playoff drought they'll need newcomer Jose Quintana to be downright brilliant in his return to the American League. The lefty was once an all-star caliber starter while with the White Sox, but a '17 midseason trade sent him to the other side of the Windy City, and his 77 starts as a Cub left a lot to be desired. After joining the Angels as a free-agent there is quite a bit of pressure on him to help solve this team's pitching woes, and how he fares will go a long way in determining how successful this team can be. 

 
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Oakland Athletics: Matt Chapman

Oakland Athletics: Matt Chapman
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For a lot of teams to be successful, they need peripheral pieces to breakout or bounce back, but for the A's, their best player is front and center. This team has talent throughout and decent depth, but if they are going to win and win often, they simply need third baseman Matt Chapman to perform at an elite level. The Cal State Fullerton product has watched his batting average and OBP both diminish for three years running and while 2020 was not a good year for anyone, Chapman could not have gone home happy when it ended. His .232 batting average was the worst of his career, and he struck out in over a third of his at-bats. The veteran remains the best defensive third baseman in baseball not named Nolan Arenado, but Oakland is cognizant of just how badly they need him to rebound offensively. 

 
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Seattle Mariners: Ty France

Seattle Mariners: Ty France
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France never really got a fair shake in San Diego, but when he was traded to Seattle last summer and got a chance to play regularly the former 34th round draft pick started to look a lot like a diamond in the rough. In 141 total at-bats in 2020 France slashed .305/.368/.468 with 14 extra-base hits, and he's carried that production into this year's spring training where he is currently tearing the cover off the ball. The Mariners are counting on the San Diego State product to be a dangerous DH for them moving forward, and if they are good this year he'll almost certainly be a big reason why. 

 
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Houston Astros: Jake Odorizzi

Houston Astros: Jake Odorizzi
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The Astros' pitching staff has a gaping hole in it entering the 2021 season with Justin Verlander shelved due to Tommy John surgery. In an effort to offset his absence at least a little, Houston signed right-hander Jake Odorizzi in early March, and they'll simply need him to be effective if they're going to continue their dominance of the AL West. Odorizzi gave the Twins probably the best season of his career in '19, going 15-7 with a 3.51 ERA and a 1.21 WHIP in 159 innings, but he lost most of last year with a variety of different ailments. It was surprising that he lingered on the open market as long as he did, but if he pitches the way the Astros believe he can, he'll be well worth the wait. 

 
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Texas Rangers: Joey Gallo

Texas Rangers: Joey Gallo
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Texas is another team that faces seriously long odds of competing for a playoff spot in 2021, especially after finishing an American League worst 22-38 a year ago. If they're going to shock the world and go from worst to first in the AL West you'd better believe powerful Joey Gallo is going to have to be front and center. The big left-handed slugger has never been a high average hitter--as evidenced by his .208 lifetime mark--but in his last two full, healthy seasons, he crushed 40 and 41 homers respectively. The Rangers will live with his 1-4's if the one is a game-changing three-run bomb. 

 
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New York Mets: Marcus Stroman

New York Mets: Marcus Stroman
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The Mets have incredibly high expectations following their fast and furious overhaul thanks to their new ownership group. This team has added one of the best players in baseball in Francisco Lindor, and also brought back a tremendous starting pitcher--Carlos Carrasco--in the same trade. They're still led by the best pitcher in baseball, though, righty Jacob deGrom, who early in spring training is looking every bit like the guy who recently won back-to-back Cy Young awards. Behind him in the rotation though, if Marcus Stroman is really good, this team will be downright scary. The veteran was dominating for the Blue Jays before coming to Queens in a mid-2019 trade, and while his numbers dipped a little in the National League he still quickly became an important part of his new squad. The right-hander opted out of the '20 campaign due to covid concerns, but now he has his sights on giving New York one of the better #2's in the sport. 

 
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Atlanta Braves: Mike Soroka

Atlanta Braves: Mike Soroka
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The Braves have continued to be a powerhouse in the National League, and for a few years in a row now they've been the best team on the senior circuit save for the Dodgers. And they actually had a 3-1 lead on LA in last fall's NLCS. A guy who quite possibly would've made the difference in the series for them would've been ace righty Mike Soroka, whom they lost to an Achilles injury in August. Soroka is probably not going to be ready for opening day, but when he comes back Atlanta will need him to pitch like the legitimate #1 he was prior to getting hurt. And if he can, perhaps this will be the October they finally get over the hump. 

 
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Washington Nationals: Carter Kieboom

Washington Nationals: Carter Kieboom
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The Nationals were a disappointment in the pandemic shortened 2020 season, struggling to a 26-34 record and failing to even make the playoffs and defend their 2019 World Series title. Heading into '21 they expect to be a lot better. This team is getting Ryan Zimmerman and Joe Ross back--both of whom opted out a season ago--, and over the winter they brought in first baseman Josh Bell, outfielder Kyle Schwarber, closer Brad Hand, and starter Jon Lester. But the most important player to this team's success, in my opinion, is young Carter Kieboom. D.C.'s first-round pick from 2016 was truly a menace for the opposition during his minor league career, shooting up prospect rankings and looking like the next star this club would develop. But in 138 big league at-bat's to date, he's hit just .181, and he'll simply have to pick it up to avoid this line-up having any black holes in it. 

 
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Philadelphia Phillies: Zach Eflin

Philadelphia Phillies: Zach Eflin
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As always, Philadelphia's fate will be determined by how well they perform on the mound, as offensively this team should score enough to win their share of games. The rotation in Philly has been a cause of concern for several years now, and for the 2nd straight season, they feature a strong 1-2 punch in Aaron Nola and Zack Wheeler, and then a lot of question marks. The Phillies desperately need someone to step up and be a reliable #3, and righty Zach Eflin is the guy they'd like to see do it. The 26-year-old has shown flashes across parts of five big-league seasons, but he still owns a lifetime ERA of 4.63 and prior to last summer had never struck out over a batter/inning.

 
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Miami Marlins: Sixto Sanchez

Miami Marlins: Sixto Sanchez
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Miami acquired right-hander Sixto Sanchez in their well-documented J.T. Realmuto trade with the Phillies a few years back, and after making his debut last summer the young hurler looked every bit like the future ace the Marlins hoped he would be. In seven starts he put up a 3.46 ERA with a 1.21 WHIP, and his season was highlighted by a dominant complete game (albeit in a seven-inning doubleheader), against his former organization. The Marlins have steady rotation presences in Sandy Alcantara and Pedro Lopez, but Sanchez has the highest ceiling of any pitcher in their organization, and they're hopeful he'll develop into a bona fide ace over the next several weeks/months. 

 
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St. Louis Cardinals: Nolan Arenado

St. Louis Cardinals: Nolan Arenado
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Nolan Arenado has become the latest star to depart the NL West for St. Louis, joining longtime Diamondback Paul Goldschmidt who arrived here two years ago. The tremendous third baseman had grown unhappy in Colorado, and this winter he got his wish of a fresh start somewhere else. For a five-year period from '15-'19, there simply was not a more productive offensive player in the NL than Arenado, who drove in at least 110 runs in all five years, while belting a cumulative 199 home runs. The only knock on him has always been that his home splits in Denver obviously appeared buoyed by Coors Field, but here's his chance to end that talk in a hurry. 

 
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Chicago Cubs: Kris Bryant

Chicago Cubs: Kris Bryant
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Chicago's 3rd baseman has been the subject of countless trade rumors over the past two winters, and at this point, it's safe to lean towards his future being somewhere else sooner rather than later. That is unless the script is dramatically flipped in the next few months. After a solid 2019 campaign, Bryant struggled mightily in the shortened '20 season, slashing only .206/.293/.351 with four home runs. The Cubs still won the NL Central but were then swept unceremoniously by Miami in the first round. For them to win in 2021 they'll need Bryant to get himself back on track and perhaps in turn begin to mend this relationship. 

 
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Cincinnati Reds: Tyler Mahle

Cincinnati Reds: Tyler Mahle
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The Reds went all in last offseason in an effort to end a long playoff drought, and while they were successful in qualifying for the postseason, their stay didn't last long. Now entering 2021 their outlook has changed a bit. Cy Young-winning righty Trevor Bauer has departed for Los Angeles, and their top two bullpen arms from a year ago, Raisel Iglesias and Archie Bradley, both call new cities home. Cincinnati still has a solid top of the rotation, led by Sonny Gray and Luis Castillo, but Bauer's presence here made them a scary team to face in a short series. This is why a lot of pressure will now be on young Tyler Mahle to pick up the slack. In 10 outings a year ago the 26-year-old pitched to a strong 3.59 ERA in 47.2 frames, but he's never reached 130 innings in a big-league season, and he's certainly never been asked to be a #3 starter. 

 
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Milwaukee Brewers: Christian Yelich

Milwaukee Brewers: Christian Yelich
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Christian Yelich was the MVP of the National League in 2018 and was arguably even better the following year before a late-season injury essentially did him and the Brewers team in. But during the truncated 2020 campaign he just did not look like himself. Playing in all but two of Milwaukee's games, the 29-year-old hit only .205, and while he did reach base at a .356 clip and connect on 20 extra-base hits in 200 at-bats, it was not the season he envisioned for himself. Heading into '21 the NL Central features a bunch of teams in transition and lacks a clear-cut favorite. If Yelich can return to his MVP form this Brewers team should be in the mix.

 
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Pittsburgh Pirates: Ke'Bryan Hayes

Pittsburgh Pirates: Ke'Bryan Hayes
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When talking about how the Pittsburgh Pirates can be successful this season, it's important to point out just how much success is relative in this situation. Baseball's worst team is not going to compete for a playoff spot, meaning what would be a success for them would not be for most other teams. With that in mind, nothing would represent more of a positive for this team in 2021 than the continued development of young third baseman Ke'Bryan Hayes. The 2nd generation big leaguer earned his first call-up on 9/1 last year, and from the moment he stepped on a Major League field he never stopped hitting. In 85 at-bats the youngster slashed a fabulous .376/.442/.682  with five homers, seven doubles, and two triples. Pittsburgh and its fans are anxious to see what he can do with a full season. 

 
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Los Angeles Dodgers: Trevor Bauer

Los Angeles Dodgers: Trevor Bauer
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Trevor Bauer was going to face enough pressure already after turning his free-agent process into a Lebron James-esque decision, but he's made things even harder on himself by attempting to pitch with one eye closed during spring training to the confusion of opposing teams. Bauer obviously brings a big personality with him to LA, but he's also joining a team that just won the World Series and intends to repeat. How well he can back up his career year will in large part determine if they can do just that. 

 
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San Diego Padres: Drew Pomeranz

San Diego Padres: Drew Pomeranz
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The San Diego Padres were the definition of a team going all in this winter. The Friars massively upgraded their starting rotation by bringing in Yu Darvish, Blake Snell, and Joe Musgrove, signed Korean superstar Ha-seong Kim away from the KBO, and fortified their bullpen with the additions of Mark Melancon and Keone Kela. But even after all of that, it's unclear if they've done enough to even catch the Dodgers in the NL West. This is why left-hander Drew Pomeranz, who is expected to close games in San Diego in 2021, is going to be arguably the most important player on this team. The veteran was brilliant a year ago, dominating to the tune of a 1.45 ERA with a 1.02 WHIP across 20 outings, and he'll have to every bit as good moving forward. It's likely going to take close to 100 wins to earn the NL West division crown, and the Padres can ill afford to let games get away late. 

 
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Colorado Rockies: Trevor Story

Colorado Rockies: Trevor Story
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With the aforementioned Nolan Arenado now in St. Louis, shortstop Trevor Story has become the unquestioned face of the Colorado Rockies team. For now. To many, Arenado's departure signals the start of a full rebuild that will soon see Story and outfielder Charlie Blackmon joining him as former Rockies. But in the meantime, if this team is going to have any chance of competing in 2021 they'll need Story to play at probably an MVP level. In the shortened season a year ago he swung the bat very well, slashing .289/.355/.519 with 11 homers, 13 doubles, and four triples. But don't forget that was with Arenado hitting behind him. With less protection in the line-up, it will be interesting to see how the 28-year-old fares. 

 
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San Francisco Giants: Buster Posey

San Francisco Giants: Buster Posey
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Like the rest of the teams in this division, when compared to the Dodgers and Padres the Giants are exceedingly likely to be little more than an also-ran in 2021. San Francisco has players with resumes on their roster, but with the exception of Mike Yastrzemski, most of their name players are on the wrong side of their prime. Like catcher Buster Posey for example. The '12 NL MVP has not really played at an all-star level for several years, and he opted out of the 2020 season out of concern for his newly adopted twin daughters. Posey is a truly good guy in the game and someone who is easy to root for, and it would be quite a story if he could turn back the clock and help keep San Francisco in a race this summer. 

 
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Arizona Diamondbacks: Madison Bumgarner

Arizona Diamondbacks: Madison Bumgarner
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Speaking of Giants' icons whose teams need them to turn back the clock. The Diamondbacks shockingly signed southpaw Madison Bumgarner away from the Bay Area prior to last season, but his first year in the desert was a disaster. In nine starts the veteran pitched to a career-worst 6.48 ERA with a dreadful 1.44 WHIP while allowing the opposition to hit a gaudy .276 against him. The Diamondbacks already face an uphill battle to compete, and they simply won't be able to do it without Bumgarner pitching like he did in his prime. 

Justin Mears is a freelance sports writer from Long Beach Island, NJ. Enjoys being frustrated by the Mets and Cowboys, reading Linwood Barclay novels, and being yelled at by his toddler son. Follow him on twitter @justinwmears

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