Wednesday, December 29, 2010
The Fall and Rise of Joba’s FastballA few weeks ago we looked at some data on Joba’s slider over the last 3 seasons. Here’s a look at his fastball over that period.
The drop in velocity isn’t news. Joba lost about 3 ticks on his fastball in 2009. However, 2010 saw a bump in velocity. This could be a sign that Joba’s arm is rebounding from the shoulder issue that occurred in August of 2008. Then again, a full season of bullpen work, rather than 150+ innings as a starter could have something to do with it.
The vertical movement (PVZ) on Joba’s fastball increased each season, but this is probably attributed to his drop in overall velocity. It’s odd that the horizontal movement on his fastball against lefties continues to drop, especially considering that the red on his heat map (scroll below) seems to edge inward each year (again, a righty throwing a fastball inside more will get a higher reading on his PVX due to the angle of the pitch when crossing the plate). However, a closer look shows that he threw far less inside fastballs in 2010, as the light blue is nearly all gone inside on his heat map to LHB. Thus, while the bulk of his pitches may have been moving in off the outside corner, Joba avoided throwing as many inside fastballs to LHB last season.
There are a number of other factors that may account for this phenomenon, including a possible change in release point and whether Joba altered where he set himself on the rubber. And as SG pointed out, some of the variation may be due to calibration or systemic error rather than any change on Joba’s part. From the data I’ve seen from the rest of the league so far, I’d say that the pitchFX software has been fairly consistent over the last 3 years. I wouldn’t count out some calibration issues, however, any actual deviation resulting from hardware issues over the course of a season is probably minor given the bulk of the data.
A look at the following graph shows that Joba’s fastball velocity rose steadily throughout the 2010 season.
Again, we can only speculate as to the cause, although I’d love to think it’s mainly due to his shoulder fully healing. But more than likely it’s a combination of a decreased workload and a buildup of arm strength.
Lasty, here’s a look at Joba’s heat maps for the last 3 seasons.
You can see that in 2009, Joba’s fastball was catching the inner half of the plate a bit more, particularly against RHB. Combining this with a considerable drop in velocity was deadly, as his .570 SLG% against points out. His 2009 fastball against RHB also caught the upper half of the zone much more, particularly on the mid to outer half of the plate. This is typically a bad place to leave a 92 mph fastball.
In 2010, Joba’s location to RHB changed dramatically as he threw his fastball to a much lower spot, nearly abandoning the upper half of the zone. Doing so shaved over 150 points off his SLG% against to RHB.
Every week that passes seems to indicate that Andy Pettitte is more likely to retire. The Yankees need to fill out their rotation. Now, I understand that this isn’t the same JOBA! of 2007-08. But it might not be the worst thing in the world if the Yankees began to transition him back to a starting role at some point, especially if his arm truly is getting stronger.
Since Boston has already locked up the 2011 AL East title, what’s the harm?
All heatmaps and data courtesy of the In Depth Baseball analytics platform
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