FanGraphs Baseball


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  1. It amuses me that Ruben Tejada and Prince Fielder are tied in this stat.

    Comment by Sylvan — December 17, 2012 @ 1:25 pm

  2. Muh man, Bill Petti.

    Comment by James Gentile — December 17, 2012 @ 1:25 pm

  3. Seems to me this could be important for playoff performance. A more consistent team being less likely to go cold at the worst possible time.

    Comment by CK — December 17, 2012 @ 1:32 pm

  4. What are you trying to answer here? There’s a -.787 correlation between your VOL and PA/G. This makes lots of sense if you think about the wOBA per game method. With Jeter leading the league in PA’s per game, the value of a randomly distributed 15 HRs will be divided by a significantly larger denominator. This makes him look consistent when in fact you’re just getting larger sample sizes for each wOBA datapoint you are taking the standard deviation of.

    If you are really asking who gave the most consistent value to his team day in and day out, this is fine. You are describing what happened well. That said, if you were were trying to see what hitters give value in a lumpier distribution, you might want to control for the major factors of batting order, and how often a lineup will get around and drive up PA/G.

    You could order all PA outcomes from least valuable to most valuable and take a Gini coefficient of the players’ distribution of total value, or you could more simply tack on the basepath outcome to hitting outcome of each PA and take wOBA/PA, but right now you’re telling a good deal about where this player batted in a lineup and how good the team around him was in addition to how he produced his value. Also, you’re stat interestingly demonstrates through the correlation with PA/G that managers are attuned to the factors of consistent production (high OBP, good running, lower power) in their selection of batting order.

    Comment by jfcincotta — December 17, 2012 @ 1:51 pm

  5. Very interesting analysis. Perhaps a dramatic handedness split, especially for players more optimally platooned than are being used by their clubs, could be one underlying factor in high volatility metrics (Loney, LaHair, McGehee, etc.).

    Glaring SwStr discrepancies on specific pitches as well?

    Might also be interesting to take out baserunning influence on wOBA to see how that affects the volatility of some of the “high volatility” bunch (Gomez, Parra, Morgan, etc.). Consistent SB success would likely result in less volatility, while lower OBP hitters with speed may have long dry spells between games where everything comes together for them.

    Comment by snydeq — December 17, 2012 @ 1:58 pm

  6. …and less likely to get hot at the best possible time.

    Comment by Jon L. — December 17, 2012 @ 2:09 pm

  7. Very cool and interesting, Bill.

    I guess when I think of ‘volatility’, I tend to think ‘streakiness’, and so I am surprised that Jay Bruce’s VOL is just a bit higher than average as he is one of the streakiest players I’ve witnessed. But, of course, his streaks last months instead of days.

    I realize ‘streakiness’ is a totally different thing in this context, but I do think it would interesting to also look at time increments of greater than 1 day, such as a week, or, if it is possible, increments of ~20 PA or something. Unless there are already metrics measuring this that I am unaware, of course.

    Comment by gweedoh565 — December 17, 2012 @ 2:19 pm

  8. How would a player who has extended hot/cold streaks appear in a metric like this? That is, he may be relatively consistent day to day. But a few times during the year he undergoes a massive shift in his production. It would seem that the scale (daily) of the volatility metric could have a significant bearing on its interpretation.

    As a Reds fan, I’m constantly arguing with my fellow fans about whether or not Jay Bruce is inconsistent. He seems to go through long slumps throughout much of the season, interrupted occasionally by a stretch where he’s the best hitter in baseball. And yet, here he shows up as a mild 104.


    Comment by RMR — December 17, 2012 @ 2:35 pm

  9. Just as a follow-up. Of the 25 “most volatile hitters of 2012″ only eight are not in the bottom 10 percent of at least one of the standardized pitch value categories (wFB/C, wSL/C, wCT/C, etc.), based on min 300 PA.

    (Presley, McGehee, Carpenter, Moreland, Colvin, Chavez, Guzman, and Maxwell)

    Comment by snydeq — December 17, 2012 @ 2:42 pm

  10. great minds, RMR!

    Comment by gweedoh565 — December 17, 2012 @ 2:55 pm

  11. Kudos to this stat. I’m a fan.

    Comment by Pinstripe Wizard — December 17, 2012 @ 3:33 pm

  12. Have you considered running a fangraphs version of the Sharpe Ratio using this data? In case you don’t know, the Sharpe Ratio is a risk-adjusted performance metric that is used to measure investment performance; seems like it would be a simple enough conversion using wOBA and the VOL metric. That sort of information would be incredibly useful in a weekly head-to-head league. It should also be fairly simple to construct.

    Comment by Brandon S — December 17, 2012 @ 3:45 pm

  13. Considering that you will in theory be facing the toughest pitchers in the playoffs, I don’t know if “relying on guys getting hot” seems like a great strategy. If I could bank 3 runs in every game and just play defense, I’d win more often than a team who averages 4 runs a game but relies on a long tail to have that number (since it doesn’t matter if they score 4 runs or 4,000 to beat my sure-bet 3). Any distribution of run scoring is going to be truncated (unless you find a way to score less than zero), so volatility in run scoring is mainly going to be extending that right tail.

    Comment by B N — December 17, 2012 @ 3:47 pm

  14. Conversely, a less consistent team being more likely to get hot at the best possible time.

    Comment by MangoLiger — December 17, 2012 @ 3:56 pm

  15. B N– relying on guys to get hot isn’t a great strategy for the playoffs… it’s the only strategy. Too few samples. Hottest team wins.

    Comment by MangoLiger — December 17, 2012 @ 4:04 pm

  16. Stepping back a little bit from the model / stat itself, I’d be interested in some of the implications here. Are more volatile players more likely to polarize their fan base? (e.g. I go to a game, Nyjer Morgan makes a couple great plays, I leave thinking he’s pretty great despite his numbers; my friend goes to two games in a weekend series, sees a bunch of bad contact, thinks he needs to go)

    Another thought: Todd Helton ranks very highly on your since-1974 VOL- leaderboard — but in recent seasons has put up a wOBA far below his prime (he’s just below 300 PAs last season). What has his VOL- curve looked like as he’s aged?

    Comment by rusty — December 17, 2012 @ 4:18 pm

  17. So I know someone over at THT did a study years ago looking at something similar for pitchers, and found that out of two equally productive SP, the more volatile one was more valuable to the team, meaning he allowed for his team to win more games, since he had more games of excellence than the other pitcher. I think he was looking at AJ Burnett. So my question is, how does hitter volatility relate to team wins? Is it better to have more volatility if it means more games of high-end wOBAs, and therefore helping your team win more games?

    Comment by Mike — December 17, 2012 @ 5:30 pm

  18. it seems strange to see david wright among the “least volatile” hitters, when his offense basically dropped continually all year

    Comment by jim — December 17, 2012 @ 6:37 pm

  19. This is pretty well-established: the better team wants to be consistent, because they’ll win games when nothing goes crazy. The worse team wants to be streaky, because they might as well try to get hot rather than lose on the slow grind.

    Comment by CJ — December 17, 2012 @ 6:44 pm

  20. I’m not sure if measuring “volatility by PA” will tell us much useful that we need to know either; can it really capture anything that’s not already measured by various rate statistics, like essentially H/PA, 2B/PA, BB/PA, HR/PA? In other words, would it really give us that much more than a combination of average, on-base, and ISO?

    Comment by Haishan — December 17, 2012 @ 7:43 pm

  21. Generalizing for the purpose of developing playoff strategy at this time is inane.

    A. Here’s the length and breadth of the best strategy we have right now for the playoffs: “Make the playoffs”

    B. This research is in it’s infancy. It’s premature to draw any conclusions from it.

    Comment by Garrett J — December 17, 2012 @ 11:49 pm

  22. Wow.

    Comment by Erix — December 18, 2012 @ 12:26 am

  23. Agree. All he is currently measuring is the ratio of small events (single and walks) to large events (extra base hits). This is already pretty obvious from glancing at a guy’s stat line. Volatility needs to be measured over a fixed number of observations. So for players with a similar stat profile, who has exceptionally high or low per-30-PA (for example) volatility? And is it predictive?

    Comment by PM — December 18, 2012 @ 1:03 am

  24. I like this research, Bill, but two questions come to mind:

    1. Is VOL a skill? It looks like it is, but there’s got to be SOMEONE at the top and/or bottom of a bell curve. I suggest the old Tom Tango/The Book method: Find the leaders and laggers in year X, then check their tendencies for years X-1 and X+1, but there are lots of ways to check that correlation, YMMV. I THINK it’ll end up up correlating, but it may very well take longer than a season to do so.

    2. How do you correct for power? Certainly, wOBA is a decent metric but what strikes me is that you’re going to run into “volatility” created merely by the value of a home run. Don’t forget there are several zeroes in the normal distribution (it’s kinda like a normal distribution – is there a name for a normal bell curve that’s constrained by 1/2?) image at the top of your page, mainly because it’s not possible to put out a wOBA of 0.05 in one game, (and apparently it’s HARD to put out a wOBA of 0.50 in one game though not impossible.)

    By the same token, most power is expressed as home runs, and you can’t have HALF a home run. It just seems to me that you can easily run into what you call volatility, but is in reality the limitation of how granular you can get with some of a player’s contributions: Consider that a guy who goes 1 for 4 with a HR and nothing else has posted a daily wOBA of .487, a nigh-unreachable number for his yearly average. 1 for 5 with a HR is slightly more reasonable, at .390.

    I very much fear that you’ll see players with low volatility who just happen to have a yearly average wOBA that is extremely close to a common daily number, like .390 (1/5, HR) or 0.360 (2/5, two singles.)

    Some cursory examination shows that there exists a weak correlation (r-squared = 0.166) between VOL and ISO:

    I didn’t have time to identify all of the “low-hanging-fruit” for daily wOBAs, the most common numbers like .360 and .390 (those two are just brown numbers – they may not even be all that common)

    I’m curious about that. What’re the most common daily wOBAs and how are they arrived at?

    Comment by Garrett J — December 18, 2012 @ 1:27 am

  25. Also the massive difference between 1/4, HR and 1/5, HR really makes me sad. Guys who have a good day at the bottom of the lineup are much more likely to post 4PA days than guys at the top of the lineup, but is there really a difference between a guy who hits 3 home runs over 12 AB from the 8 spot (4 games) and a guy who hits 3 home runs over 12 AB from the 2 hole (3 games?) Not really, but STD( daily_wOBA ) will probably suggest there would be.

    Comment by Garrett J — December 18, 2012 @ 1:31 am

  26. Exactly, We are dealing with a sample size issue here. Taken to the extreme, a player with 1 PA/G and a player with 4 PA/G both make exactly 1BB, 1 K, 1 HR, and 1 GIDP every 4 PAs, one will have a VOL of 0, the other will have a VOL of… I dont have a calculator, a lot.

    Comment by David — December 18, 2012 @ 1:46 am

  27. Oops, I missed the section about the correlation already in the article. Apparently my first question (is it a skill) had already been answered.

    Comment by Garrett J — December 18, 2012 @ 2:00 am

  28. This might be more valuable run with WPA. Its too late for me to actually think about things, but that might round out some of the rough edges by including more data in the sample…? That makes me think though, they need a WPA with defense, Id like to see the run value of trout climbing the wall

    Comment by David — December 18, 2012 @ 2:01 am

  29. I find this so interesting I will overlook the wale of a spelling error in the very first sentence… unless some people are really looking for an albino version of Olubowale Victor Akintimehin’s award-winning rhymes?

    Comment by B N — December 18, 2012 @ 1:27 pm

  30. Thx

    Comment by Bill Petti — December 18, 2012 @ 1:28 pm

  31. Well, the primary difference is that the guy hitting 3 HR in 4 games from the #8 spot might be worth putting higher in the lineup ;)

    Comment by B N — December 18, 2012 @ 1:29 pm

  32. Very very interesting analysis. This is something I’ve often thought about.

    Another question I have is whether players who have less volatility are rewarded in free agency at a higher rate already than players of higher volatility?

    With regard to team performance it seems likely to me that, given two teams with equivalent wOBA on offense and identical run differential, that the team with lower VOL will not necessarily outperform the team with higher VOL. However, it does seem likely that the team with lower VOL will consistently have less variance to their overall record than the team with higher VOL.

    In that way, as somebody said before, if you’re a team with weaker talent it might behoove that team to construct itself with a inherently higher VOL lineup in order to attempt to “get lucky” and reach the high end of the variance in any given year. Vice versa it would appear a team with more talent would prefer to construct a lineup with lower variance to minimize its chances of hitting the low end of there possible outcomes.

    Comment by Colin — December 18, 2012 @ 5:53 pm

  33. I’m pretty new to this, so I apologize if the answer to this question is obvious. What is the reasoning behind transforming the VOL stat so it isn’t corellated with yearly wOBA? I’ve been trying to reason it out on my own, and my best guess is that a high wOBA player (so, a better player?) has more opportunity to have a higher wOBA volatility, or std. dev., because his bad days are as bad as everyone else’s, but his good days are better. So, by transforming VOL you get a measure of daily wOBA volatility that isn’t correlated with player skill and you can compare VOL regardless of skill level. Am I even close?

    Comment by CW — December 18, 2012 @ 11:25 pm

  34. CW,

    Yes I think you hit the nail on the head. Bad players are more likely to have low variance. As a result, variance probably does have a somewhat strong correlation to ability. We don’t want to measure ability or rather, we want to avoid measuring ability so the metric is changed so that there is no correlation.

    Comment by Colin — December 19, 2012 @ 5:03 pm

  35. Very interesting approach; nicely done. Even before reaching the data, the back-of-the-envelope skill that seemed to fit your description of VOL was ability to maintain a hitting streak — it needn’t be a high cutoff like 20 games, but batters that you’d be unsurprised to have a slew of smaller hitting streaks during the season (say, 5 games at a time, just to throw a number out there). All of the VOL leaders from last season and the last few decades easily fit that description.

    Comment by Christian — December 20, 2012 @ 11:24 am

  36. “This meant that simply looking at something like the standard deviation of daily performances risked creating a metric that was biased against hitters with a higher seasonal wOBA. I tried a few different things, but I still ended up with metrics that were highly correlated with seasonal wOBA.”

    Can someone briefly explain to me why the standard deviation of daily performance would be biased against high wOBA players?

    Also, is it just coincidence that the league average VOL is .500?

    Comment by Justinw303 — January 3, 2013 @ 11:33 am

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