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  1. Jeff, I looked into this in a slightly different way last year, specifically in regards to Hanley and Miguel Cabrera. It’s at:

    Great article.

    Comment by Bryan Grosnick — February 1, 2013 @ 3:11 pm

  2. Maybe the norm is that if you DON’T lose weight your natural tendency is to perform worse defensively as you age. So losing weight allows a player to maintain the status quo…

    Comment by salvo — February 1, 2013 @ 3:41 pm

  3. I don’t know how to do this better, but considering many of these players missed significant time in either 2011 or 2012, and defensive metrics are already suspect when looking at single years, I’m not sure how meaningful this is.

    Additionally, I honestly just don’t believe that actually losing weight would not be a benefit, so if there is a story here I think it is something you somewhat touched on but did not say explicitly: players are liars.

    Comment by TKDC — February 1, 2013 @ 3:50 pm

  4. Could using DRS instead solve some of the sample size issues?

    Comment by Alex — February 1, 2013 @ 4:05 pm

  5. I would fully expect Peralta’s UZR numbers to take a significant hit in 2013, just due to natural regression. Does anyone really believe he was the third best defensive SS in the league last year? Didn’t think so. So, when the numbers aren’t as sparkly, let’s not attribute the difference to his weight- or lack thereof.

    Comment by tigerdog — February 1, 2013 @ 4:30 pm

  6. A 236 lb SS? Good lord. Easy on the buffet there Jhonny.

    Comment by Mike — February 1, 2013 @ 4:32 pm

  7. Several years ago, Peralta came into camp touting off season laser surgery for his eyes as a projected benefit to his hitting in the upcoming season. He’s definitely a guy who looks for new angles to improve.

    Comment by rustydude — February 1, 2013 @ 4:49 pm

  8. You should have compared 2010 Pablo Sandoval to 2011 Pablo Sandoval. He lost like 50 pounds and improved +12 runs over the previous year.

    Comment by M'n'M's — February 1, 2013 @ 4:50 pm

  9. No kidding!!! I’m a 220lb financial risk manager and that’s considered beefy for this profession.

    Comment by kevinthecomic — February 1, 2013 @ 4:51 pm

  10. “DRS characterizes him as being about a league-average defensive shortstop. UZR characterizes him as being an above-average defensive shortstop.”

    They don’t work very well then.

    Sometimes it seems that stats like UZR and DRS might be revealing something that can’t be easily observed with the naked eye. Sure, stats are great for that, but these defensive metrics are obviously wrong often enough that I wonder if we’re not just better off without them.

    Comment by Dan — February 1, 2013 @ 5:00 pm

  11. Bad conclusion. Your evidence certainly doesn’t prove that. I wouldn’t be at all surprised if weight loss significantly improved defense especially for certain positions (not 1B)

    Comment by Cliff — February 1, 2013 @ 5:10 pm

  12. I would like to see how this correlates with age. It seems to me that the players who lost weight (and gained weight, for that matter) were all a year older that year than they were the previous year. They probably should have been at least slightly worse defensively in year 2. The fact that their defensive performance was roughly the same may indicate that the weight loss worked to counter the effect of aging. In other words, it might mean that losing weight worked because the players would have been worse due to age had they not lost weight.

    Comment by chuckb — February 1, 2013 @ 6:04 pm

  13. Where did I say anything proves anything

    Comment by Jeff Sullivan — February 1, 2013 @ 6:09 pm

  14. Yes, I talked about that in the article

    Comment by Jeff Sullivan — February 1, 2013 @ 6:10 pm

  15. 236 is more than a lot of heavyweight boxers. Crazy.

    Comment by Bryan — February 1, 2013 @ 6:48 pm

  16. didn’t really keep it off, tho, did he?

    Comment by brendan — February 1, 2013 @ 6:52 pm

  17. An ambitious study with a tough to prove goal but an admirable attempt. One of the greater issues being the difference in the physical demands of each position i.e: comparing Miggy to Heyward or Inge to Fowler seems a bit unfair.

    Still, nice work though. Certainly worth considering

    Comment by Cisco — February 1, 2013 @ 7:07 pm

  18. What I’ll never understand is athletes making millions of dollars needing to be told to get in shape. Shouldnt Peralta assume that, oh I don’t know, that because he’s a SS maybe he should be relatively agile?

    Comment by Brandon R — February 1, 2013 @ 7:26 pm

  19. Peralta almost never makes errors. Admittedly, he doesn’t look very smooth in the field, but that elite error avoidance is where those numbers are coming from.

    Comment by The Party Bird — February 1, 2013 @ 7:34 pm

  20. Do you have the change in offensive production by those same groups? It’d be interesting to see any gains/losses there measured against the changes in defense.

    Comment by Dennis — February 1, 2013 @ 7:40 pm

  21. Net Gain/Loss Ht(Inches)
    Swisher -3.7 71
    Choo -15.4 71
    Byrd -3.9 72
    Moustakas +12.3 72
    McGehee -9.7 73
    Longoria -14.6 74
    Desmond +8.2 74
    Hunter +11.3 74
    Reynolds +5.8 74
    Cruz +4.1 74
    Bruce -3.5 75
    Teixeira +3.8 75
    Cabrera +5.6 76
    Morneau -8.7 76
    Smoak +3.1 76
    Heyward +7.3 77

    Comment by Voice of Reason — February 1, 2013 @ 8:27 pm

  22. There, you did it again, tsk tsk tsk

    Comment by Meister — February 1, 2013 @ 8:44 pm

  23. My guess is that it’s easier to shed the weight in the off-season because there’s not as much late night eating and drinking.

    Comment by Circlechange11 — February 1, 2013 @ 11:17 pm

  24. Fantastic article! Lots of statistical analysis with a horrible conclusion! Can’t wait until you guys get your hands on HOF votes.

    Comment by TroutFan — February 1, 2013 @ 11:23 pm

  25. Post some random data-mining and conclude with “well, we really can’t know anything for sure.” The Fangraphs way.

    Comment by Oscar — February 2, 2013 @ 1:58 am

  26. TroutFan and Oscar, there’s nothing wrong with reporting a lack of definitive findings or a negative finding. In fact, it’s essential to any experimental process that we determine which hypotheses are correct, which are incorrect, and which need more study.

    Just because the “data mining” or “statistical analysis” doesn’t lead to some ground-breaking discovery doesn’t mean it’s not worth reporting what you find — it can inspire others to approach the same question from a new angle.

    Comment by BookWorm — February 2, 2013 @ 8:48 am

  27. Yes, because it’s clear that the HOF would get way worse by swapping out the current set of voters.

    Comment by Rustydude — February 2, 2013 @ 8:58 am

  28. Seeing Prince and Cabrera around your infield might not be a great incentive to lose weight. Peralta probably thought he was pretty nimble compared to these guys, even at his linebacker weight.

    Comment by Darrell Berger — February 2, 2013 @ 10:26 am

  29. Fu*king Scientific Method, how does it work?

    Comment by Someone — February 2, 2013 @ 10:41 am

  30. Fantastic comment! Absolutely worthless!

    Comment by TKDC — February 2, 2013 @ 10:50 am

  31. Defensive statistics are garbage.

    Comment by Adam B. — February 2, 2013 @ 10:54 am

  32. Hadn’t thought of it that way, Darrell, but that is one beefy infield. How much did the 2B weigh?

    Comment by Baltar — February 2, 2013 @ 12:10 pm

  33. Yep, just traveling puts on the pounds, too. What do you do on an airplane or in an airport? Probably not eat and drink in a healthy fashion.

    Comment by Baltar — February 2, 2013 @ 12:16 pm

  34. He’s earned his millions and he is considered one of the very best in the entire world in his profession. I can certainly see why he wouldn’t worry about his weight too much.

    Comment by Ervin Santana — February 2, 2013 @ 1:26 pm

  35. Commies. Thats how. Theyre gonna brainwash our youth to ensure their future world domination.

    Comment by Yokel — February 2, 2013 @ 1:27 pm

  36. Yep. And evolution. Absolutely garbage. And our country’s morals because we don’t have mandatory school prayers.

    Comment by Yokel — February 2, 2013 @ 1:28 pm

  37. feed not the trolls, they know not things

    Comment by commenter #1 — February 2, 2013 @ 1:35 pm

  38. To an extent this seems to depend on what you’re good/bat at. For instance, if the players problem is he makes too many errors, losing weight might not really help him.

    Peralta’s problem is that he lacks some range. Peralta happens to be very good at making plays when he gets the opportunity to do so. So I tend to believe it might help him get to a few more balls.

    Comment by Colin — February 2, 2013 @ 2:09 pm

  39. I agree. I think the lost weight will definitely help his range. Especially with the little things, like turning double plays. If he’s making more difficult plays, he might make more errors though. Even if that’s the case, it would be nice to see the effort.

    Comment by JChang — February 2, 2013 @ 3:30 pm

  40. “i want conclusions, dammit!!
    don’t bother me with all your facts.”

    Comment by craigws — February 2, 2013 @ 4:50 pm

  41. I notice that 3 of the players (Longoria, Morneau, and Choo) who lost weight and saw big declines in their defensive numbers also missed significant time do to injuries.

    Comment by HtWP — February 2, 2013 @ 5:45 pm

  42. In addition to the caveats you cited, here’s more: Your comparator groups.

    Among the players who lost weight who you cite, only one was a middle infielder shortstop or even a middle infielder and he saw a marked improvement in UZR, Ian Desmond. The rest of the group are largely corner outfielders and infielders and may not make suitable comparators to a shortstop.

    Your weight-gain group is meant to test whether there is an opposite effect but that would only hold some validity if those players went from being out of shape to in-shape. But some of these players did not — they went from being skinny to adding some muscle — Andrus is a prime example.

    Finally, while Peralta’s total defensive rating changed only marginally in 2012 his UZR range rating improved a much more substantial amount that was offset by a worsening in error rating. If the point of his weight loss was to improve his range and if you believe such small samples of UZR, then his weight loss achieved its intended effect.

    Comment by Jonathan Sher — February 2, 2013 @ 8:27 pm

  43. @Baltar – Depends on when in the season. If you’re talking about Ryan Raburn, about 180 lbs of completely dead weight.

    Comment by gnomez — February 2, 2013 @ 8:29 pm

  44. Exactly. Peralta doesn’t have much range, but within his range, he’s incredibly consistent, and also has a pretty good arm for a shortstop.

    Actually, your quote sounds almost verbatim like something Jim Leyland said.

    Comment by gnomez — February 2, 2013 @ 8:30 pm

  45. Earlier, I was looking at fielding runs based on Revised Zone Rating and Out-of-Zone plays using a method that Colin Wyers developed a few years back. I don’t know that this method is any better than any other defensive metric, but the results for Peralta made sense. According to this, he was one of the best in baseball in the zone (steady) and one of the worst outside the zone (no range). Combining the two, he was -3 runs below average.

    Comment by Lee Panas — February 2, 2013 @ 9:12 pm

  46. So do advanced fielding stats have value or not?
    According to the numbers Peralta was indeed a solid SS last year, yet many commenters disregard them because they don’t fit their narrative. When some argued during the MVP battle that Trout ain’t Willie Mays and throws like Johnny Damon, the pro-Trout group point to the positive fielding numbers to fit their narrative. Can’t have it both ways…if UZR can’t be trusted yet, why use them?

    Comment by tbonemacd — February 3, 2013 @ 12:15 am

  47. For what it is worth, if a player or group of players is -3 in UZR one season and -3 the next season, that implies a loss in UZR talent. That is because -3 for one season or a partial season needs to be regressed, perhaps half-way towards a mean (say, zero), which puts their year X UZR true talent at -1.5. So a -3 next year means a loss of 1.5 runs in UZR talent.

    That, BTW, is entirely consistent with aging. Players lose 1-2 runs a year in UZR talent at almost any age (due to aging – UZR peaks quite early, probably in the early 20’s).

    Comment by MGL — February 3, 2013 @ 12:46 am

  48. What are you talking about? The samples are the same size. Both years would get regressed equally. Why would you assume that a -3 in year 2 is somehow more indicative of true skill than the -3 in year 1? If a group of drivers of unknown skill got into 10% more accidents than average in a given year, then the next year they also had 10% more than average, you would claim that they actually lost skill between years 1 and 2? Interesting. By that logic, a team that goes .450 win pct. in year 1 is a lot better than the same team that goes .450 in year 2 (assuming same roster and no aging)? That’s not the way it works. You have more data, so all you can say is that the true talent is closer to .450 than you first thought (after year 1). However, you cannot say that the players got worse from year 1 to 2.

    Comment by evo34 — February 3, 2013 @ 2:22 am

  49. Downvotes are weird. Is there a single piece of genuine insight in this article? Is there anything in it that justifies posting it?

    Seriously! Read it! There is nothing in it!

    Comment by Oscar — February 3, 2013 @ 2:46 am

  50. Data mining is great. But this article has no ACTUAL statistical analysis. No strength of correlation, no nothing. It’s an arbitrary sample of some numbers and then no attempt to prove, disprove, demonstrate, or anything. I wouldn’t even be posting if it wasn’t a frustrating trend for Sullivan and a lot of the others on this site. Compare this to a Dave Cameron article, or Tom Tango or Dave Studeman or Mike Fast or Pizza Cutter or etc etc.

    There’s no original insight, there’s no rigor. It’s fluff. And after the twentieth one of these in two weeks, I get annoyed. This is not the scientific method.

    Comment by Oscar — February 3, 2013 @ 2:49 am

  51. Seems to me like if you wanted to try getting any kind of meaningful analysis with this you would have to get much better information on players weights and break them up into groups based on their height to weight ratios.
    First off you don’t know which of your players kept the weight off for more than a few weeks into the season and which put it back on or even gained more weight.
    Second, you don’t know which of your players would have been considered overweight to begin with. You have young players on there who may have actually been considered underweight who merely gained muscle weight. That’s fairly different than an overweight player with too much fat.

    It seems kind of lazy to try to do this kind of analysis without really gathering the necessary data and just lumping together what little you found without thought of whether what you were comparing is actually comparable.

    Comment by mike — February 3, 2013 @ 8:36 am

  52. All these little things add up to make a whole. If there are fans that do not believe analysis is important, no problem, don’t come here.

    Take the team that takes this stuff seriously, put them against a MLB team that doesn’t take this stuff seriously, and have them battle for 100 years and see who comes out on top.

    I imagine it will be the one, consistently, that takes as much data as they can and try to see what they can learn from it.

    Comment by Givejonadollar — February 3, 2013 @ 3:13 pm

  53. Forget his defense, hopefully his 18 pound loss helps him swing the bat a little quicker. Just gimme 275, not asking for much!

    Comment by Kevin — February 3, 2013 @ 7:27 pm

  54. Minus three for Peralta passes the smell test. He’s probably not close to as good as UZR thinks he is, and he’s certainly much better than fans who only look at range think he is. Fringe average overall.

    Comment by The Party Bird — February 3, 2013 @ 10:19 pm

  55. I look at Jhonny’s effort to lose weight and effort to try to increase his range (I don’t think “range” can be taught) and say that he sees a really good thing happening in Detroit and he wants to his best to be a part of it. If his hittiing last year was an anomoly, and I think it was, he will be a valuable part of a championship team. If he bats 7, there should be men on base when he comes up, RBI’s should go up also. We certainly don’t have any shortstops in the pipeline if we read ann article about Cale Iorg, he can’t hit my wife’s weight, let alone mine, which would be a good average!! That makes Jhonny look all the better unless someone is willing to part with a good shortstop for Porcello or Smyly…I say let’s keep all three!

    Comment by Alaruss1942 — February 4, 2013 @ 8:26 am

  56. We agree that this isn’t ‘statistical analysis,’ in the sense that there is no attempt to do a rigorous, parametric correlation of something like weight-change and UZR.

    But my point is that one needs to start somewhere. Jeff’s article could be the first step in a conversation about where to take this for further research. And frankly, given that the information on a player’s weight is self-reported, I’m not sure there’s much better that can be done. But an article without a firm conclusion one way or the other could be seen as an invitation to do further research.

    Comment by BookWorm — February 4, 2013 @ 10:25 am

  57. Sit on one’s ass.

    Comment by Andrew — February 4, 2013 @ 11:50 am

  58. You should definitely ask for your money back.

    Comment by Chris from Bothell — February 4, 2013 @ 4:36 pm

  59. I wonder what type of effect weight loss/gain has on older players and their injury probabilities. Packing some extra pounds can do some real damage to the ol’ knees, especially for older players who play physically demanding positions. If losing 18 pounds makes it less likely that Peralta suffers an injury, then even if there is no effect on his overall defense, the ability to play in more games creates a positive effect overall.

    Comment by AdmiralWhiskers — February 4, 2013 @ 4:47 pm

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