The results are a bit disappointing, but it is important to see if this is just random bad luck, or a slight regression of Chamberlain’s skills. One disturbing sign is that his line drive rate is up. Over 20% of the balls put in play off of Chamberlain are line drives, compared to 14.2% last season. Another warning flag is opponents contact. Opponents are chasing less pitches outside of the strike zone (a 3% drop from 2008,) and making more contact on pitches in the zone (a 6% increase.) A rise in line drive rate and better pitch recognition from the opposition are often traits of worsening stuff: either his off speed is flattening out, or his fastball is losing velocity. In Chamberlain’s case, it’s a little of both. His average fastball velocity is 92.5 MPH this season, down 2.5 MPH from 2008. Velocity on his slider is down almost an entire tick as well. His breaking pitches aren’t moving as much this season as opposed to last season either. Particularly troubling is that Chamberlain’s slider on average has a full four inches less of vertical movement (.9 feet last season, .5 feet this season.) Nearly half the bite on his out pitch has vanished.
It seems clear that Chamberlain is not the pitcher he was last season. I don’t believe that he’s completely recovered from his shoulder injury he suffered last August against Texas. All of the warning signs present in his velocity drops this season were there in the few relief appearances he made after rejoining the team last September. Unfortunately, we have no starts from that time period from which to make a comparison, but it does not seem like he ever regained the mojo he had going last year. He is still a functional major league pitcher with his current arsenal, but if he doesn’t get back the snap he had on his slider, or the pop on his fastball, Joba Chamberlain might be looking at a much less stellar career.
Tonight might not have been the best night to create a piece on Joba Chamberlain’s struggles. He had one of his better starts, throwing eight strong innings against a very capable Tampa Bay Rays team. That said, the criticisms above are still valid. It would ridiculous to extrapolate one start to either say ‘he’s great!’ or ‘he sucks!’ For what it’s worth, Chamberlain’s velocity is still down, and his break wasn’t as sharp. I’m not trying to take anything away from a good overall performance, but the process he is going through right now just isn’t as good as it was last season. As good as his start was, that shouldn’t be enough to distract from the larger picture.