Top 10 MLB prospects who could make an impact in June

While Reyes will technically make his debut before June, his impact will be felt on the Cardinals' midseason fight within the NL Central starting June 1. On the mend from Tommy John surgery 15 months ago, the former top prospect blazed his way through a rehab assignment, running up 44 strikeouts over 23 scoreless innings scattered over four starts.

In his first MLB start in over a year, Reyes’ electrifying stuff carried over, holding the Brewers scoreless over four innings while striking out three.

2. Michael Kopech, White Sox

Amid a lost season for the White Sox, there will be plenty of opportunity for the organization’s many promising prospects to cut their teeth in the majors. Of that substantial group, Kopech should be on the shortlist to make his debut.

The 22-year-old fireballer owns the minors' best fastball, which regularly dials up past 100 miles per hour and helped him average 11.6 strikeouts per nine innings thus far in his pro career. With the White Sox boasting the majors’ second-worst ERA from its starting pitching, there are fewer obstacles than ever blocking his ascent.

3. Eloy Jimenez, White Sox

Jimenez is destroying minor league pitching currently, hitting .444 during a nine-game hitting streak that has included a pair of home runs, four doubles and a triple. He is decimating Double-A pitching and may not need a stop at Triple-A Charlotte before making his way to Guaranteed Rate Field. His raw power and increasingly mature approach at the plate could allow him to make a quick impact in Chicago.

4. Shane Bieber, Indians

Bieber’s presence with the Tribe in June is assured, as he is slated to make his MLB debut on Thursday after owning all comers thus far in 2018. Between Double-A Akron and Triple-A Columbus, Bieber produced a 5-1 record and 1.10 ERA while batters managed only a .183 average against him. Cracking the Indians’ rotation is not an easily accomplished outcome, but the polished arsenal of Bieber could keep him in the fold for the long term.

5. Nick Senzel, Reds

Coming into the spring, it looked as if Senzel was on the fast track to break through with the Reds, but a nasty bout with vertigo curbed him for much of the early part of the year, cutting into his productivity. For the time being, Senzel has put the issue behind him and has returned to action, where he is seeing time at both second and third base. If his bat continues on the form that has made him one of the game’s top 10 prospects over the past two years (.310/.389/.508 split over 894 plate appearances), he could again find himself on the fast track to Cincinnati — especially if the club parts ways with incumbent second baseman Scooter Gennett.

6. Kolby Allard, Braves

Could it somehow be possible for the Braves to have yet another wunderkind on the way short of drinking age? Allard stands in as a resounding "yes" to that question. The young southpaw is mowing down hitters five to six years older than him on average. After working to a 4-1 record with a 2.09 ERA over his first 10 starts, the temptation to call once more on the incredibly fruitful minor league ranks could be too much to pass on.

7. Willy Adames, Rays

After a brief May promotion provided an enticing preview of coming attractions, June should see the full-time ascension of the Rays’ shortstop of the future. An all-around threat who is capable being a heart-of-the-order bat for Tampa in addition to bringing a smooth glove to either middle infield position, Adames profiles as a long-term fixture for the club at shortstop. After the Super 2 deadline passes in mid-June (and clubs get the additional arbitration year that facilitates), Adames will likely be back for good.

8. Adbert Alzolay, Cubs

The starting rotation of the Cubs has left much to be desired in the early going, with the additions of Yu Darvish and Tyler Chatwood underwhelming thus far (4.52 ERA over 102.2 innings). This could open an opportunity for the team’s top prospect to get a shot at cracking the staff soon. While the 23-year-old is still working at refining his secondary pitches, giving Alzolay a chance before potentially jumping into the trade market toward the deadline makes a lot of sense.

9. Willie Calhoun, Rangers

With the Rangers speeding toward a rebuild, finding time for the players who will be on hand beyond this summer will become a priority. Calhoun was the key return in the trade that sent Darvish to the Dodgers last August and showed well in a brief stint in Arlington last fall. He swings a mature bat and can fill in as a corner outfielder, although designated hitter could be his more immediate destination. There are few reasons for the Rangers to go much further forward without getting Calhoun in the mix.

10. Sandy Alcantara, Marlins

Alcantara, who was the prized return from the Cardinals in exchange for Marcell Ozuna, has skyrocketed to the top of the system in his new home. In his most recent outing, the 22-year-old allowed one run over seven innings while giving up two walks and striking out three. While he still has some development to do as a total product, his raw ability, coupled with the lack of talent in all parts of the Marlins’ staff, could allow him to at the very least crack the Miami bullpen very soon.