Yes, boys and girls, today's article will be about BABIP.
/pauses for collective groan
The reason we're discussing BABIP is to take a look at what's going on so far this season with several of the Rockies' pitchers who are seemingly poor given what we know of their careers, and pitchers who are seemingly amazing, given what we are to be expecting of them.
Before we dive into the real numbers, let's take a step back and re-examine BABIP and what it means to us. BABIP stands for Batting Average on Balls In Play. What that means is it's counting H/AB for any ball that's put into play, isn't a walk, strikeout, or home run. Another way of looking at it is that it's how many hits drop that are subject to the fielders, the stadium, luck, etc etc etc.
Now, BABIP can be incorrectly framed as just the lucky hits, the seeing eye grounders, the no-man's-land popups that fall between 3 fielders, every baseball that Adam Dunn can't get to but doesn't clearly make an error on - you get the idea. BABIP also accounts for screaming liners that split the gap, perfectly laid bunts down the 3B line when the fielder is playing behind the bag, left-handed drives that roll into the RF corner, or in other words: good hits.
A player with a high BABIP is typically just eschewed as being lucky or playing against poor defenses, whatever. A batter that is posting a high BABIP (or a pitcher that is allowing one) could be just as easily awesome (or terrible) as they are lucky (or unlucky). Flip things over, and a pitcher that is allowing a miniscule BABIP (or a batter that's hitting for one) is bound to come back to earth in some way shape or form, and more of those hits are likely to drop. Obviously, this goes back to my favorite mantra of "If you're ever wondering what a hitter or pitcher is going to do at any given time, just refer to their career line".
We're all familiar by now with the concept of the Three True Outcomes, which are a Strikeout, Walk, or Home Run (even though some Home Runs are truer than others...), but if you're not, let me explain. The reason that these are True Outcomes is that they are purely a pitcher-batter interaction, and have absolutely nothing to do with the players on the field. When the 3-ball pitch misses outside, it doesn't matter if Brooks Robinson is manning the hot corner, the batter is trotting to 1B. Once the man behind the plate calls Strike 3, I don't care if Franklin Gutierrez is patrolling CF, the batter is going to sit down. Whether or not Ozzie Smith is ranging up the middle, if that ball clears the fence in fair territory, runs are scoring. Granted, there are a few caveats, such as DeWayne Wise saving Mark Buerhle's Perfect Game, or a dropped 3rd strike that allows a runner to reach 1st somehow. They happen so rarely that the concept of Three True Outcomes still holds.
So now that we have our TTO tool back in our handy-dandy toolbelt of baseball statistics, we can move on to BABIP.
Click past the jump and we'll get this party started.
BABIP is everything that TTO is not. The formula, which you'll see directly below, pulls out homers and strikeouts, and it's only measured in terms of at-bats, so the Base-on-Balls isn't factor anyhow.
It's a pretty simple formula, and its use is just to get an idea of what batters are doing against a pitcher, when compared to peripherals. To get a good statistical picture of what a pitcher is doing, we need to look at both peripherals and BABIP to get a full-ish idea of his performance. Typically, a league-average BABIP is somewhere in the .290-.300 realms, so anyone massively different than that is probably going to regress one way or the other.
So let's start with Rafael Betancourt. He is posting a 5.56 ERA right now, and at first blush, he'd be the first to be crucified when we begin to talk about pitching woes. The first step in my particular method of evaluation is to throw out a reliever's ERA. When I say that, I don't mean for the entire bullpen, but given the nature of a relief pitcher's job, ERA is just such a volatile metric to use as a baseline, I have trouble really using it confidently. I mean, if a guy is posting a season ERA of 9 come June, yeah, there's cause for alarm. Looking at a bullpen's ERA as a whole seems far more fair, as a starter will pitch more than half of the game, and the bullpen will pitch the rest, so you have a better body of work to look at.
Anyhow, Raffa. After I've ignored his ERA, I look at his peripherals. He's posting a K/9 of 10.32, which is well above his career line, a BB/9 of 1.59, which is well below his career line, and a HR/9 of 0.79, which is more or less in line with his career numbers, a bit better. So what this is telling me here is that Raffa is actually pitching BETTER than his career norms. So what Raffa is doing to the batter is pretty dominant still. I should also mention that Raffa is throwing 2.43 strikes per ball, so if we wanted to try and bring out the whole "well he just doesn't throw strikes" argument, it doesn't take effect. In fact, the next highest Strike-Ball ratio belongs to Matt Belisle, at 1.94.
But much as I throw out ERA for an individual reliever, a high ERA is still going to be an indicator of something going wrong. When you have peripherals as outstanding as Betancourt's, and you're still posting a plus-5 ERA, we need to look at BABIP. Right now, Raffa is allowing a BABIP of .425, which is absolutely far from being excellent or even acceptable. We look at his LD% (line-drive %) and that 32.4 compared to his 20.9% career is also pretty poor. So we add up the poor BABIP and poor LD% and we can basically infer that what batters are doing to Raffa is pretty detrimental as a whole.
So my conclusions on Betancourt? I'm not worried. Striking out that many and walking that few, he's going to come back around. Yeah, he's hanging a few, yeah, guys are getting hits off of him where they normally wouldn't, but it seems to me that if his peripherals are that good still, he's doing what he does well, he just needs to refine it a bit. His Pitch F/X doesn't seem out of line at all, so I'm doubting it's a mechanical problem, it seems to just be that whole "fastballs down the middle of the plate" thing that's hurting him. Given his career .300 BABIP, I think he's gonna come back down to earth and going to be ok.
Now let's flip this evaluation over and look at the other side of BABIP - the unsustainably good. This evaluation is so much less fun to look at than the previous one. When a pitcher's ERA is worse than his peripherals, you know that he's performing better than the results might show, and you know that eventually the results and the performance will start to match up. The other sign of the coin is when a pitcher is performing worse than results, because like above, you know that the results will eventually mirror the performances.
The example we're going to use for this is Manny Corpas. Before I continue, this is not a "MANNY CORPAS RAGE" kind of analysis, it's more nailbiting than that.
Corpas is striking out 6.56 per nine innings, walking 3.47 per nine, and allowing 0.77 per nine. The K9 is slightly better than his career line, the BB9 is well above his career line, and his HR9 is surprisingly low given what we know of him already. Essentially, his peripherals are saying that he's doing a decent job. So despite what I typed above about peripherals/performance discrepancies, Manny isn't the perfect example, because as I just said, he's doing alright. However, similar (albeit slightly worse) peripherals yielded a 5.88 ERA in 2009 and a 4.52 ERA in 2008, as compared to his 3.09 this season. Now, while I throw out ERA as an absolute measure, it is still useful as an indicator of where something might not be matching up.
Now the fun part: BABIP. Corpas is posting a .184 BABIP, which as we can tell by comparing it to his career .305 BABIP and the league average BABIP (.290-.300, somewhere in there), that's gonna come skyrocketing sooner than later. I believe this even stronger when we look at some of his batted ball percentages. His LD% is down, which is great, I'm a big fan, and hope he can hang on to that. His GB% is WAY down though, which scares me, and his FB% is WAY up, which similarly scares me. On top of that, his HR/FB% is also low, which makes me wonder when some of these fly balls are gonna start leaving the park. I know, LOLCORZ or whatever, but this evaluation works for everybody. A low HR/FB% combined with a high FB% combined with a low BABIP is a bull ringing the doorbell of your china shop.
What scares me about this is that Corpas seems like he's due to start getting hit harder, more frequently, and we just handed him the keys to the 9th inning. Granted, it's not as if Franklin Morales is really wowing us with his performances thus far, and if Manny can somehow sustain unsustainability, I'll be rooting for him.
As a final thought to this piece, BABIP is not the know-all-end-all of statistical evaluation. I don't pretend to be able to predict the future based on BABIP, or else I'd be incredibly rich and wouldn't even have time to write for Purple Row. What BABIP is, when stacked on peripherals, is simply an indicator of an inflated or deflated performance from a given pitcher. Manny held up an entire season with a .260 BABIP, so maybe he'll come down to earth just a bit and suddenly be awesome again. I'd love to see it.
The numbers just don't support it.