A Joba Wrapped In A Mystery Inside An Enigma

After last season, I wrote a post comparing Joba Chamberlain and Daniel Bard, pointing out that their peripherals were incredibly similar and that Joba projected to have much better results than he did in 2010 going forward. Yet, here we are 6 weeks into 2011, and once again Joba’s peripherals far outstrip his results. He continues to be an enigma with stuff that suggests an ability to be dominant out of the bullpen but results that are middling at best. Let’s take a look at his statistical profile to see whether we can discern why there is a disconnect between his stuff and his results.

Joba’s ERA is 4.05 and his FIP is 3.93, but his xFIP (the best of the 3 for projecting future ERA) is 2.79 and he has only allowed 2 of 7 inherited runners to score. Joba’s strikeout rate is actually down from last season (7.65 from 9.67), but he has made up for that by generating a lot more grounders than he has in the past (59.3% compared to 46.2% career) and limiting walks (1.80 BB/9, lowest of his career). He is only allowing one baserunner per inning, and although he has a low BABIP (.250), he also has a depressed line drive rate (14.8%) that can help explain the decreased BABIP. Taken together, he is missing bats, inducing groundballs, and generally encouraging weak contact. So what’s wrong?

The answer is fairly obvious, as the only real anomaly in Joba’s statistical profile is his current home run rate. He has allowed 3 home runs in 20 IP, good for a career-high 1.35 HR/9 and an obscene HR/FB% of 21.4%. When it comes to relievers, a few bad pitches can totally skew ERA and suggest performance much worse than it has been. Looking forward, it is reasonable to expect Joba’s HR/FB rate to return to the more typical 8-10%, which would make his overall line look significantly better.

One last thing I wanted to look at was Joba’s stuff, to see whether there is reason outside of the peripherals to expect better results than we saw in 2010. What I found is fairly encouraging. Using Pitch f/x data, we can see that Joba is not using his fastball as much as he did last season (from 65.3% to 55%), eschewing it in favor of the slider (28.2 to 32.3%), curveball (5.3 to 9.9%), and changeup (0.1 to 1.8%). One of the most frequent complaints about Joba’s transition to the bullpen has been that it turned him from a four-pitch pitcher into a limited two-pitch guy. It seems that he is trying to recapture the curve and has also started to reincorporate the changeup. Furthermore, a 10% in fastballs suggests that he is no longer trying to simply throw everything past hitters, and is instead using his good breaking stuff to keep them off balance, which will allow all of his pitches to play up.

Looking at the quality of Joba’s stuff itself, the most significant change has been to the slider. Friend of the blog and BtB writer Lucas Apostoleris provided the following information on Joba’s seemingly reborn slider:

Joba has thrown his slider 96 times this year, elicited a swing on 51 of those pitches, and a swing-and-miss on 25. On a per swing basis, that’s a whiff rate of 49%. That’s almost back to where it was early in his career (but please be mindful of the small sample size!):

2007: 65.3% (not full season data; PITCHf/x wasn’t installed for all games at all parks until 2008)
2008: 51.5%
2009: 42.8%
2010: 39.4%
2011: 49.0%

Anecdotally, Joba’s slider had looked flat for the past two seasons, missing the “drop” it had prior to his shoulder injury in 2008. Lucas actually looked at this issue prior to 2011, and found that Joba had in fact lost vertical drop on his slider over the last two seasons. A look at the Pitch f/x data shows that he has recovered an inch of break on his slider in 2011, which may be leading to the return to form in the swinging strike department that Lucas highlighted above.

Finally, although Joba’s average fastball velocity is about the same as it was last season (94.6 to 94.3), that number is likely skewed by low velocity outings that occurred during the frigid early weeks of the season. His average velocity over the last 3 weeks is 95.6mph, which is about 3/4 of a MPH higher than it was over the same span last season. This graph from Mike Fast over at BP (h/t to Lucas) displays Joba’s increasing velocity in 2011, and comparison to 2010 does seem to show a slight increase over the same point last year:

Taking all of this together, I am fairly optimistic about Joba moving forward. His stuff looks better than it has in a while, his peripherals are excellent, and his ERA is inflated by a handful of bad pitches that have lead to an unsustainable HR/FB rate. I still believe that Joba Chamberlain can be a dominant reliever for the Yankees in 2011.