Originally written on Fangraphs  |  Last updated 11/10/14
Every year, around this time, players advertise themselves as being in the best shape of their lives, either because their offseason conditioning regimens improved, or because previously they were lazy. I think the players are almost always being sincere — they probably, genuinely, feel great — but as fans, we identify this as a cliche, and we generally dismiss it. For one thing, we hear this claim entirely too often. For another, it’s never been demonstrated that there’s a relationship between best shape and on-field success. Or, if you prefer, on-field improvement. It’s been studied, albeit not exhaustively so. There’s something particular I want to examine, though, and it has to do with Jhonny Peralta. This is an article about Peralta from Friday morning. Within: Fewer pounds would be preferable, they told him, as he headed home for the winter. He got the message and lost 18. “It’s good,” Peralta said. “I’ve never been at this weight since I’ve been with Detroit. I finished last season at 236. I’m at 218 now.” Peralta continues: “Dombrowski and everybody wanted me working on my range,” he said. “That’s why I tried to get lighter. So I can be quicker, especially up the middle.” It’s funny — everyone, a year ago, was prepared for the Tigers’ infield defense to be dreadful, what with having Prince Fielder and Miguel Cabrera at the corners. It was pretty bad, especially if you ask Rick Porcello (off the record). But at least according to the numbers, Jhonny Peralta was fine. DRS characterizes him as being about a league-average defensive shortstop. UZR characterizes him as being an above-average defensive shortstop. People talk about Peralta’s limited range, but overall, it doesn’t seem like there’s much to complain about. But we can proceed anyway. Peralta wants to get better at defense, so he says he lost weight. A pretty significant amount of weight, for that matter, and he says he lost it in a healthy way. It’s intuitive how weight loss and better conditioning could make a defender improve. But I was curious whether we could find anything in the numbers if we looked at previous examples. So I pulled up some previous examples. I identified 16 players who, between 2011 and 2012, claimed to have lost at least ten pounds. They lost this weight on purpose, and it wasn’t because they were ill or anything. I wanted to know what happened with their defense, so I put their season-before and season-after Fld + Pos numbers over a denominator of 1,000 innings. In this way, I get UZR, and I also account for changes in position. A year ago, did weight loss lead to defensive improvement? Player Pre-loss Post-loss Casey McGehee 6.9 -2.8 Evan Longoria 10.9 -3.7 Ian Desmond 1.1 9.3 Jason Heyward 3.5 10.8 Jay Bruce -5.7 -9.2 Justin Morneau -3.1 -11.8 Justin Smoak -10.8 -7.7 Mark Reynolds -21.8 -16 Mark Teixeira -2.6 1.2 Marlon Byrd 3.9 0.0 Miguel Cabrera -12 -6.4 Mike Moustakas 2.2 14.5 Nelson Cruz -12.1 -8.2 Nick Swisher -0.2 -3.9 Shin-Soo Choo -2.4 -17.9 Torii Hunter -7.7 3.6 AVERAGE -3.1 -3.0 Welp. Hard to get less meaningful than that. Some players got better, and some players got worse, but, overall, there was virtually no change within the group. What they were, defensively, in 2011, they were again defensively in 2012. Now for the caveats. For one thing, you know about the issues with UZR. For another thing, you know about the issues with a small sample size. And what we don’t know is what these players would’ve done in 2012 if they hadn’t lost weight and trained as they did. We don’t have a control, so it could be that the -3.0 post-loss average is significant. All the players got a year older, and as players get older, defense declines. As a group, the defense didn’t decline, so that’s of interest. But we definitely don’t see a strong effect. If there’s a benefit, we’re talking about a very small handful of runs, probably. Something to consider is the somewhat arbitrary nature of reporting baseball player weight. It’s not always listed accurately, and sometimes players report weight loss from the previous spring, while sometimes they report weight loss from the end of the year. Additionally, offseason conditioning matters only so much — all players train in spring training, and then weight can change over the course of the regular season. A player who’s lost, say, 15 pounds come the beginning of February could see his weight change again in the coming months. Just for the heck of it, how about the players who, between 2011 and 2012, added a significant amount of weight? The table is the same as the table above. Player Pre-gain Post-gain Brandon Inge 4.1 15.6 Carlos Gonzalez -4.1 -12.7 Darwin Barney 7.1 11.9 Dexter Fowler -3.7 -11.9 Elvis Andrus 10.6 11.5 Franklin Gutierrez 21.6 -23.9 Freddie Freeman -17.7 -11.6 Pablo Sandoval 13.9 2.8 AVERAGE 4.0 -2.3 You could say there might be something there. All the same caveats apply, though. It’s UZR, the sample is even smaller, the players got a year older, and the whole sample might be thrown off by Franklin Gutierrez, who didn’t play that many innings in 2012. Gutierrez was also recovering from an illness, although he was more ill in 2011, when his defense was great. If you don’t trust the Gutierrez numbers, and you remove them, the average numbers balance out. If you leave them in, you get precisely this table. It’s included more for curiosity than for analysis. We need more data, and I’m thinking about collecting it. Jhonny Peralta wants to get better in the field, so he lost a lot of weight. That’s good — it’ll make him healthier, and it could improve his durability. But we don’t have much evidence to suggest he’ll take a statistical step forward, and if you look at players who gain weight, the data also isn’t conclusive. We do need a lot more of it, however, so that’s something to keep in mind. As intuitive as it is that being in better shape could make your defense better, in reality we’re probably talking about very slight differences, if any differences at all. What’s hugely critical for defense are instincts and first steps and hand-eye coordination and arm. Losing weight could make you a little quicker, but probably not significantly so, and in Peralta’s case, it’s unlikely a matter of 18 pounds could make him more able to get to a bunch of grounders in the hole. Peralta’s range has only a little to do with his physical frame, or at least the parts of his physical frame he can change. It’s good that Peralta’s in better shape. Maybe he’ll keep that up all season. Maybe it’ll have real, meaningful benefits. I just wouldn’t expect him to channel his inner Andrelton Simmons. What Jhonny Peralta was, Jhonny Peralta probably will be.
GET THE YARDBARKER APP:
Ios_download En_app_rgb_wo_45
MORE FROM YARDBARKER

Report: Wrigley Field renovation causing massive rat problem

Rex Ryan praises Patriots, calls Deflategate 'unfortunate'

Brady hopes Peyton Manning comes back next season

Report: Thibodeau’s relationship with Bulls 'beyond repair'

Joe Montana pins blame for Deflategate on Tom Brady

LIKE WHAT YOU SEE?
GET THE DAILY NEWSLETTER:

NFLPA boss: No Deflategate interviews until after SB

Blandino: Deflategate no sting; PSI in footballs not logged in

Aaron Hernandez’s DNA found on bullet casing, joint near body

Thomas upset he was tested for PEDs over health statement

Marshawn’s press conference to end all press conferences

NFL to assist Seahawks in ID'ing Pats' ineligible receiver sets

WATCH: Timberwolves throw shade at Kevin Love in promo

Tom Izzo: 'The Twitter' may have affected team's confidence

Measles outbreak hits Arizona days before Super Bowl

Proposed pace-of-play rule changes, by the numbers

Super Bowl XLIX should smash TV viewership record yet again

NFL, officials, Carroll disagree on ineligible player rules

Seattle business rolling 12,000 joints for Super Bowl

How Yardbarker got Marshawn Lynch to open up back in 2008

Super Bowl records that won't fall anytime soon

Richard Sherman, girlfriend expecting baby any day

15 amazing Super Bowl XLIX stats

Pats fans buy Super Bowl tickets, told they're unavailable

MLB News
Delivered to your inbox
You'll also receive Yardbarker's daily Top 10, featuring the best sports stories from around the web. Customize your newsletter to get articles on your favorite sports and teams. And the best part? It's free!

By clicking "Sign Me Up", you have read and agreed to the Fox Sports Digital Privacy Policy and Terms of Use. You can opt out at any time. For more information, please see our Privacy Policy.
the YARDBARKER app
Get it now!
Ios_download En_app_rgb_wo_45

Rex Ryan downplays Deflategate

Brady hopes Manning comes back

The worst Super Bowl commercials of all-time

SB anthem, halftime performers through the years

Super Bowl should smash TV records

Super Bowl records unlikely to fall

15 amazing Super Bowl XLIX stats

Teammate: Manziel not a joke

Ten most underrated SB performances

Knicks ‘in play’ for Kevin Durant?

Ex-QB: Everyone deflates footballs

Where did 'Hawks, Pats find players?

Today's Best Stuff
For Bloggers

Join the Yardbarker Network for more promotion, traffic, and money.

Company Info
Help
What is Yardbarker?

Yardbarker is the largest network of sports blogs and pro athlete blogs on the web. This site is the hub of the Yardbarker Network, where our editors and algorithms curate the best sports content from our network and beyond.