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Jake Peavy’s Big Secret

January 12th, 2009 by Melvin

Jake Peavy has a secret buried deep within his 2008 performance. The secret isn’t easy to see, although that has to be true because it’s what defines a secret.

Sabermetricians are pretty good at finding this type of hidden knowledge. One method of finding truth and escaping prejudices in a player’s pitching ability is to use a statistic called tRA. This metric breaks the result of every plate appearance down to a level that allows us to accurately assign credit or blame to the pitcher.

Some of these plate appearance results tRA takes into account are line drives, fly balls, pop-ups, home runs, strikeouts, and walks. Again, the purpose here is to value as accurately as possible the influence on run prevention that pitchers have direct control over. tRA is park and league neutral, and set to the same Runs per 9 innings scale as ERA, a statistic that does poor job predicting future success compared to tRA.

This is a similar process to the FIP stat, though tRA incorporates more detail. Here is more information on tRA, along with some background from Dave Cameron about why ERA isn’t as great as you might think.

Ok, I promised a Jake Peavy secret, and you want one ASAP, am I right? Here you go:

Jake Peavy’s tRA
Year tRA
2004 3.23
2005 2.91
2006 3.65
2007 2.78
2008 4.02

See that there? See the number that jumps out a little bit? Maybe a little jumping? Holy crap. I flipped a lid when I saw that 2008 number.

Seriously, don’t tell anyone. Call me paranoid and delusional, (ok, I’ll call myself paranoid and delusional) but it isn’t an accident this wasn’t posted until after the deals with Atlanta and Chicago fell through.

Though he probably employs more complex metrics than tRA, this information clearly corroborates why Sandy Alderson has held tight to his position that trading Jake is first and foremost a baseball move.

Of course Peavy’s unsightly tRA isn’t the only reason to make the trade. As we’ve mentioned in previous posts, his age, the many needs within the organization, a poor chance the team will compete next year, and the injury risk of pitchers are all motivating factors.

When you couple this reasoning with the the Padres passing on trade opportunities with two teams, and at least one passable offer from the Braves, it makes me think that someone making the case that trading Jake is primarily about lowering payroll has a lot more explaining to do.

An ERA that seems likely an abberation, and the other reasons mentioned above mean that now is a good time to make the right deal for Jake Peavy. Unfortunately, neither the Cubs nor the Braves seem prepared to offer value the Padres prefer. Hopefully Jake’s hidden slump doesn’t manifest itself in a higher ERA come July next season.

Posted in hot stove, players, statistics | 11 Comments »

11 Responses to “Jake Peavy’s Big Secret”

  1. Ray Lankford says:

    I still think we should trade him so that he doesn’t make more than a quarter of the team’s payroll.

  2. Ray Lankford says:

    In layman’s terms, the more Luis Rodriguezes that are going to be in the starting lineup.

    But really, the Padres are looking at $29M for 39 players. And from there, it’s $20M for 38 players after Giles. Without a great minor league system, it’s pretty difficult to build a winning team from there.

    (Add to this the $10.5M that are going towards Young, Adrian, Gerut, and bench player Scott Hairston, and Towers has less than $10M for 34 players. Not to make a bailout joke, but the Padres are going to need some of that government cheese if they’re going to do anything.)

  3. Ray Lankford says:

    Also, not to blow your mind or anything, but Fangraphs has posted value wins for pitchers.

    Jake Peavy 2008: 1.9
    Javier Vazquez 2008: 5.3

  4. old_padre says:

    How much of a predictor of future performance is a stat if it has swung back and forth by at least 20% over the last four seasons?

    • The various incarnations of ERA measure lots beyond a pitcher’s control. FIP and tRA look at stuff we know a pitcher has a large degree of control over, which gives the stat more predictive value.

      Of course there are some things even stats can’t predict, like Jake’s lingering elbow injury in 2006.

  5. old_padre says:

    Even if I give you the injury in 2006, jump in the way-back machine, set it for 12 months ago today, and let me know what the highly-predictive tRA numbers say for what we should expect to see from Jake in the coming (i.e., past) season. For that matter, do the same thing if you set the date to 1/14/2005.
    My point is just that you may not want to confuse a one-year number for a trend or predictor.

    • Point taken.

      I’m not saying trade him now just because his tRA rose. I’m saying it’s another reason (a valid reason) to throw on the pile.

      But I’m really not the expert on tRA who is qualified to have this discussion. What I try to do is relay what’s going on in the world sabermetrics to fans who might not otherwise hear about things like tRA.

      I would love to hear the results of a discussion with Graham MacAree regarding your criticisms.

      I would be willing to post them on the blog as well.

    • old_padre says:

      Mr. Macaree,
      I was recently introduced to tRA through a blog post elsewhere written about Jake Peavy. I got into a bit of a conversation with they blogger who suggested I pass my question on to you.
      His implied belief about tRA is that because it analyzes all components of the batter/pitcher interaction is that it is more useful as a predictor of future performance. The question I asked in the comments is “How much of a predictor of future performance is a stat if it has swung back and forth by at least 20% over the last four seasons?”
      Now, as I read your primer, I don’t know that you would make the assertion that it’s a more accurate predictor of future performance just because it paints a more accurate picture of past results. However, if you DO feel that’s the case, could you help me understand why I saw such significant variance (I say that without having enough time or competence to truly do regression analysis or to look at deviation numbers) in the year-to-year tRA numbers for Peavy and the other guys I listed in the comments.
      I’ll admit I’m not that bright (I’m a Padres fan, how smart could I be???) and it’s been far more years since I used SPSS than it was months that I used the damn thing, so my statistical prowess is not, ahem, remarkable. However, I would love to try to understand better.
      tRA obviously isn’t a perfect future performance indicator – but nothing that we have is a perfect performance indicator. Every stat suffers from large swings year-to-year – if you look at the variation in ERA and compare it to tRA’s, you’ll find that the former’s is much higher. In fact, tRA is something like 2.5x as stable year to year as ERA, and also beats FIP (the most common ‘advanced’) pitching stat by a fairly healthy margin. So although it’s prone to large variations, it’s still more predictive than looking at other stats. Baseball is just too variable for any statistic to remain static.
      I hope that clears things up.
      Thanks, Graham. I appreciate that you replied SO quickly!
      I certainly didn’t mean to imply that I thought there was no value, or that because it has some variance, it isn’t predictive at all. I guess my beef is more with the tack taken by the blogger… look, his tRA ballooned last year, quick trade him before anyone notices.
      It may be of some interest to you that one of the alternate names for tRA in development was ‘the Jake Peavy is amazing stat’.

      Personally, I think that a ballooning tRA is a large red flag, but it’s certainly not the only thing that should be considered.

  6. old_padre says:

    To illustrate further that tRA doesn’t seem any more predictive of future performance, here are some four-year (2005-2008) running tRA lines for some top guys (ERA+ in parenthesis). I’ve tried to go with guys who haven’t missed any significant time in that period…

    Sabathia: 4.25, 3.71, 3.87, 3.15 (104, 140, 143, 162)
    Webb: 3.53, 3.61, 3.80, 3.36 (126, 152, 156, 139)
    Santana: 3.23, 3.69, 3.87, 4.16 (155, 161, 130, 166)
    Oswalt: 3.80, 4.16, 4.22, 4.06 (144, 149, 138, 120)
    Lowe: 3.66, 4.07, 3.94, 3.66 (114, 124, 118, 131)

    If we were sitting here last January and I’d given you the 2005-2007 tRA numbers and asked you to predict 2008 performance, it would have been just as much of a crapshoot for you as if I’d given you the ERA+ numbers.

    That tells me it isn’t very predictive.

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