May 14, 2012 at 12:13 pm by Franklin Rabon under Atlanta Braves
One thing I’ve heard a few stat-y people talk about with the Braves starting pitching has been the staff being unlucky. Usually they will trot out the fact that the Braves pitching staff currently sports one of the 10 worst FIP/ERA ratios in MLB (it was in the bottom three until the last game of the Cardinals series). On its face this sounds reasonable, as we always think that individual pitchers with extremely large or small ERA/FIP ratios will regress back to the mean (by definition the mean ERA/FIP ratio is 1) because for individual pitchers over small samples, large deviations are usually a function of luck more than anything else.
While there is more than likely quite a bit of poor luck going on here, sometimes as SABR inclined commentators, we have to remember what the stats we’re using are actually capturing. FIP is just that, Fielding Independent Pitching. So while the pitching staff may very well be pitching better than their results would indicate, that’s not the same as saying that the team’s run prevention (and thus their ERA) has been unlucky.
When evaluating individual pitchers and their value, which is primarily what FIP is used for, it’s perfectly fine to discount the defense that is playing behind them. You don’t want to punish the pitcher because he has a crappy defense, and you don’t want to reward a junkballer because he has an all-world defense either. Doing so is useful in two ways, A) you throw out the defense, and B) you throw out a lot of the bad luck pitchers get on batted balls in the field of play. However, when saying that the pitcher’s ERA should correct itself to its FIP, you not only should consider the defense, you in fact must evaluate the defense’s impact on the pitcher turning balls in play into outs.
What we know about the Braves defensively is that the outfield defense is pretty excellent, especially when it is Prado, Bourn and Heyward. But the infield defense is likely right up there with the worst in the game. Chipper is smooth, but has non-existent range, Pastornicky gets bad breaks and positions himself oddly often, Uggla is Uggla, and Freeman is like Chipper’s mirror, with perhaps even less range somehow. While a poor defense is oftentimes difficult to capture statistically, especially in small sample sizes, we do know what ‘damage’ it should cause, namely a large RA/FIP ratio. Figuring out exactly where the Braves defense lands is difficult because of how divergent the infield and outfield defenses are in quality. Infield defense is almost certainly more important than outfield defense, but just how much more important is an open question in the SABR community.
What portion of the Braves staff’s ERA/FIP ratio is bad luck and what part is poor defense? It is almost impossible to tell at this point. Right now they’re giving up about 7-10% more earned runs than their FIP would tend to indicate they should. Which though it may sound small, is actually a pretty huge number when played out over a full season. That’s a number that would likely prevent the Braves from reaching the playoffs if they keep it up. If 4% of it is bad luck, and the rest is bad defense, the Braves can perhaps live with it. However, I think given what we know about the defense, it’s a bit polly-anna-ish to think the ERA/FIP ratio will just ‘regress to the mean’ itself away. One thing does remain clear: if the Braves miss the playoffs, poor infield defense will likely be more to blame than anything Fredi does or doesn’t do.