The Zambrano/Bonderman Conundrum
A conundrum is loosely defined as anything that puzzles… so it makes perfect sense to use the term when describing the anomaly present in the ERA and FIPs of both Carlos Zambrano and Jeremy Bonderman. We’ve written about pitchers either outperforming their FIP or failing to live up to it plenty of times here, but, in probing the last three calendar years feature recently instituted on the leaders page, it appears that things tend to even out a bit. Except, of course, with regards to Zambrano and Bonderman.
Sixty starting pitchers qualified for inclusion over the last three calendar years and they produced the following averages:
ERA-FIP: 0.12
BABIP: .303
LOB: 71.8%
K/BB: 2.48
HR/9: 0.98
One standard deviation of the ERA-FIP is 0.28, meaning we can expect about 2/3 of the data to fall within the -0.16 to 0.40 range; additionally, 95% of the data can be expected to fall within the -0.44 to 0.68 range. Of the group of sixty pitchers, just two fell beyond the 95% confidence interval: Carlos Zambrano at -0.53 and Jeremy Bonderman at 0.83.
Now, one potential reason that someone like Zambrano consistently posts better ERAs than his FIP would suggest could deal with his BABIP: the average BABIP of this group in this span is .303 and Zambrano comes in at .273, a full thirty points lower. On the other end of the spectrum, Bonderman comes in at .325, over twenty points higher. In fact, when looking at the eighteen pitchers who fell beyond one standard deviation of the ERA-FIP mean, the nine higher than 0.40 ranged from .297-.332 in BABIP while those below -0.16 ranged between .269-.309.
I actually discovered whilst writing this post that a question regarding Zambrano outperforming his FIP was posed in the Inside the Book mailbag, to which MGL mentioned the possibility of him posting a lower than average BABIP after concluding that it is definitely possible for certain pitchers to post certain types of BABIPs. This is definitely the case. As MGL also noted in the mailbag, “FIP is a very good at eliminating the noise in BABIP, which allows us to get a better estimate of a pitcher’s run prevention skill, in the short run. In the long run, ERA, RA or ERC is MUCH better because it captures the differences in BABIP skill among pitchers, as well as the other things I mentioned above that contribute to a pitcher’s run prevention skill but are not addressed at all in FIP (like WP rate).”
So, one reason these two guys are constantly posting ERAs much better or worse than their FIP would suggest could be that they have posted above or below average BABIPs with enough regularity to show they have some type of control over it; in that regard, their ERA would be a better indicator of run prevention. Then again, they might not have control over their BABIP and this could all even out, but it would seem that this is a very likely cause at this juncture.
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If a significant percentage of starting pitchers had the ability to consistently produce BABIPs significantly different from .303, then wouldn’t we expect to see more than 2 out of 60 starters with FIP- ERA past the 95% confidence level? While we ought to be open to the possibility that Zambrano and/or Bonderman are exceptions, the data you presented suggests (to me anyway) that variations from BABIP really are random.
I am aware of the Tom Tippett research from a few years ago suggesting that pitchers do have some weak control over their career BABIPs (at least historically — the study didn’t focus on the current decade), so my guess is that pitchers’ BABIP isn’t literally random. I’m just saying that your post isn’t very persuasive on the matter.
Are there reasons why Zambrano and Bonderman are unique? Can we look at other pitchers who share their unique characteristics and see if their BABIPs on average differ from .303?
What type of characteristics? I’ve done work at Statistically Speaking with Pitch F/X data you should check out, showing that movement and velocity affect BABIP, with movement having more of an effect. I’m going to look at both of their movements tomorrow as well to try and find an answer to why they’ve been the exceptions.
The thing is that nobody ever said a significant amount of starting pitchers can control their BABIP… or that they have a certain skillset that usually results in lower/higher. It has just been found in certain cases that there are pitchers who have some type of control.
Dave Studeman found, for instance, that elite relievers have the ability to consistently post lower BABIPs. The movement study I did showed that those with above average vertical movement would post lower BABIPs than those with below average vertical movement, which would make intuitive sense, sense high vertical movement generally corresponds to flyballs, and flyballs have lower BABIPs. Not really trying to persuade anyone of anything, to be honest, but rather presenting these two as outliers, explaining why they’re outliers, and taking a first step towards getting to the bottom of why they consistently do it.
In my eyes the answer comes from MGL’s comment mentioned at the bottom; quite simply, over an extended period of time it’s better to look at ERA than FIP because there would be enough data to look at accounting for the BABIP differential amongst pitchers.
Unless a pitcher spent his career in front of good or bad defenses (liike, say, anyone who has pitched for the Mariners in the last three years).
There’s too much that goes into ERA, even over a long period of time, that isn’t pitching.
Yeah, to me, the FIP in a case like Zambrano’s or even Bonderman’s (or even Javy Vazquez) is great to show what their three controllable skills suggests their ERA should point towards… but the fact they’ve consistently beaten it/fell victim to it says, to me at least, there is something with regards to either their velo, movement, location, repertoire, etc, that affects the BABIP and therefore helps or hinders their actual ERA.
It’s been shown by myself and others like Jonathan Hale that aspects like velocity, movement, and location can affect the BABIP so perhaps Zambrano is taking full advantage of the cold-spots, so to speak, whereas Bonderman and Vazquez are the opposite.
Isn’t Z always among the league leaders in lowest line drive pct?
Of all NL starters over the last three calendar years, Z has the 4th lowest LD %:
1) Lowe, 15.4%, .291 BABIP
2) Cain, 17.7%, .276 BABIP
3) Webb, 17.8%, .294 BABIP
4) Zambrano, 18.0%, .273 BABIP
Eric, this seems to make a lot of intuitive sense. Reds fans have had an ongoing debate about the fates of SP Matt Belisle and RP Todd Coffey due to their high ERA-FIP and a high BABIP (also LD and HR/FB) that seem regression resistant.
The consensus, largely from an amateur scouting perspective, is that both guys were extremely location dependent rather than “stuff” dependent, leading them to get hit extremely hard when not on their best games. Compare that to a guy like Zambrano, or the Reds’ own Big Z Jr. (Volquez), whose incredible movement seems to induce weakly hit balls with greater regularity even when location is not perfect.
I have not done the research myself but others who have looked into it have seen that not only do pitchers with great movement on their pitches consistently post low line drive rates and therefore low BABIP’s, but pitchers with great late movement(Pitches that move while the ball is slightly invisible right before contact is made) are the hardest to hit well and can seem to beat the regressions that their peripheral stats indicate should be coming.
Isaac, that’s essentially what I wrote in the article and in this comments thread, as I’m one of the researchers who has been studying it. I did a whole article a couple weeks back looking at movement and its effect on BABIP as well as another on velocity and BABIP. Check them out at Statistically Speaking.