Joba Chamberlain seems to be on his last legs, if not as a Yankee, then perhaps with the big league club for a while. For the first time since he made his debut in 2007, the team appears willing to deal the young pitcher. The ever-loyal Joe Girardi has even turned against him. He announced before and after Monday's game that Chamberlain has lost the 8th inning job, his second demotion this season.
For the foreseeable future, the once off-limits Joba is now just a reserve arm in the bullpen, to be used when needed, ideally when the game is not on the line. This stunning fall from grace warrants a closer look to understand why Chamberlain is struggling, and what, if anything, can be done about it.
Unfortunately, Joba's numbers don't paint a clean picture. His ERA is 5.95, which is atrocious, but his FIP and xFIP are 3.01 and 3.41, respectively, both solid figures. What's more is that he has improved his strikeout, walk and home run rates from 2009. In '09 he struck out 7.61 batters, walked 4.35 and gave up 1.20 homers per 9 innings. This season all three figures have improved, standing at 9.99 strikeouts, 3.61 free passes and 0.64 homers per 9 innings. Any pitcher who improves his ability to strike batters out while walking fewer of them and giving up fewer home runs should be having an improved season, except for Chamberlain, whose 2009 ERA was 4.75, a full 1.20 runs better than this year.
The story of Chamberlain's woes lies right where ERA and FIP diverge, in balls hit in play. Here a clearer picture of what's going on begins to emerge. This season Joba is getting hammered, but the ball is staying in the park. His BABIP against has exploded from .320 in 2009 to .399 this year. Opposing players are hitting like Robinson Cano in April against Joba if they put the ball in play, which pretty much means if he doesn't strike them out, because he has allowed only 3 home runs all season. Taking all at-bats into consideration, opposing players are hitting .299 against Joba.
Chamberlain may be getting unlucky (really, really unlucky). The discrepancy between his ERA and his peripherals is odd for any pitcher, but it is particularly odd for him. He's pitched well in-line with his peripherals every other season he's been a Yankee. If this is all due simply to luck, to the fact that balls hit in play against Joba are finding the gaps and not fielders' gloves, then he is suffering from an especially long string of bad luck. The concept of the small sample size is abused and misunderstood in baseball's statistical circles. Chamberlain's 42.1 innings pitched on the season are, by definition, a large sample of innings because the statistical rule of thumb is to cap a small sample at 30 observations, something we had from Joba a while ago. Chamberlain may still be getting unlucky, but the data now points to a trend that defies the conventional tools even informed baseball fans use for analysis.
Joba struggled last season as well, but his problem was clear in 2009. Although his fastball is famous for its speed, it has never been a strong pitch. When Joba was at his best in 2007, according to Fangraphs his fastball was worth 1.51 runs for every 100 pitches versus 5.09 runs for his slider, his out pitch. In 2009, his fastball slowed to 92.5 mph on average, and was straight as a string, to quote Michael Kay. As a result it was actually a liability, worth -1.21 runs per 100 thrown in 2009, versus 1.30 runs for his slider. Chamberlain uses his fastball to set up his slider, but with the diminished velocity it was getting hit more.
Continuing the trend established previously, Chamberlain has actually improved on the effectiveness of his two main pitches this year, but to ill effect. His fastball velocity is up to 94.4 mph on average. Although it is still a liability, it is worth -0.75 runs per 100 thrown this year, a considerable improvement from last year. His slider is better as well, being worth 1.40 runs per 100 thrown this season (I am using values per 100 thrown to adjust for differences in innings pitched). 92.6% of the pitches Joba throws are fastballs and sliders, so he is essentially a two-pitch pitcher, and has been for his entire short career.
Although these numbers are frustrating, they help explain why the Yankees may have continued to give the ball to Joba for so long. If you remove his inflated ERA, he's improved every aspect of his game this season. Unfortunately the results have been the exact opposite of what the team would expect.
One set of data does stand out that may help to explain Joba's struggles. Opposing batters are swinging at pitches he throws outside of the strike zone 28.3% of the time, the highest rate since 2007, and they are swinging at pitches he throws in the zone 62.4% of the time, the highest rate in his career. This translates to an overall swing rate of 44.8%, which would be the highest of Joba's career by far, if not for his 2007 campaign, when he got batters to chase pitches out of the zone 35.1% of the time, no-doubt fooling them with that nasty slider, and contributing to an overall swing rate of 47.2%.
The batters aren't chasing. They're hitting. Batters are making contact on 86.6% of the pitches in the zone they swing at, which is the 2nd-highest rate of Joba's career, and they are making contact with 60.6% of the pitches outside of the zone that they swing at, far and away the highest clip of Joba's career (his previous high was last season's 55.9% rate).
I don't believe that Joba is getting unlucky. It may be a baseball platitude to write this, but I watch the games. The hits he gives up may not be home runs, but they are laser beams the fielders can't get to. From looking at this data my conclusion is that the league may have caught on to Joba's diminished slider and straight fastball (Kyle Farnsworth had a plus-velocity fastball that wasn't very effective also due to its straightness) and as result batters are swinging more. Joba is getting more swinging strikes this year, but that is only because last year players weren't chasing outside the zone. This year they are, but they are often making contact, perhaps just enough to foul off his slider, if not crushing it. This may cause Joba, who remains a strikeout pitcher, to move away from his slider, his best pitch, and use his fastball or curveball to get the out. Of course, the problem is that both Joba's fastball and curveball have been minus pitches.
Yankeeist still believes that Joba is too talented not to straighten himself out, but he clearly has some work to do to regain the trust of both the team and the fanbase.