The Fall and Rise of Joba's Fastball

A 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.

Joba’s Fastball vs. LHB

	P	AVG	SLG	Contact%	PVX	PVZ	VEL
2008	591	.284	.367	92.6%	3.4	-12.3	95
2009	1041	.286	.456	92.6%	2.2	-12.7	92
2010	419	.274	.405	89.5%	1.4	-12.9	94

Joba’s Fastball vs. RHB

	P	AVG	SLG	Contact%	PVX	PVZ	VEL
2008	494	.222	.287	74.4%	4.2	-12.3	96
2009	762	.327	.570	86.9%	3.1	-12.5	93
2010	383	.298	.404	84.9%	3.2	-12.8	95

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.

A look at the following graph shows that Joba’s fastball velocity rose steadily throughout the 2010 season.

Joba’s Fastball since 2008
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.

Joba’s Fastball Pitch Frequency
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?

Joba's Slider

I wanted to take a closer look at Joba’s numbers over the past 3 years to see if anything stood out besides the obvious loss in fastball velocity. Below is some data on Joba’s slider.

Joba’s Slider vs. LHB

	P	AVG	SLG	Contact%	PVX	PVZ	VEL
2008	157	.188	.292	47.1%	7.6	-18.3	85
2009	201	.175	.263	60.6%	6.4	-17.4	85
2010	106	.222	.444	57.6%	6.3	-18.3	86

Joba’s Slider vs. RHB

	P	AVG	SLG	Contact%	PVX	PVZ	VEL
2008	230	.159	.222	47.4%	7.3	-17.7	86
2009	353	.271	.402	63.6%	6.4	-16.5	85
2010	241	.217	.348	64.6%	6.6	-16.7	87

Joba’s pitch count obviously received a bump in 2009 because of the 31 starts he made that year. But overall, batters made better contact on the pitch than in 2008. You can also see that his slider lost a good deal of both vertical and horizontal movement in 2009. He lost nearly a foot per second of vertical movement against LHB and 1.2 against RHB, while losing almost equally as much horizontal movement.

In August of 2008, Joba went on the DL with shoulder inflammation, but returned to pitch in September of that year. I looked at the overall data on his slider in that final month and it was right in line with his pre-DL numbers (PVX of 7.8, PVZ of -18.0). So I’m not sure why he lost so much movement on his slider in 2009, but doubt the injury contributed much at all. I guess he could have been pitching through the injury in September ’08 and only felt the full effects the following season. But I doubt the Yankees training staff would have allowed this to happen. At this point, we can only speculate/complain about the extent his shoulder injury affected his performance.

However, Joba’s heat maps show that location may have been part of the problem with his slider.


You can see that his slider was not dropping out of the zone nearly as much in 2009. It’s possible that since he wasn’t getting as much movement on his slider, it hung in the zone more after 2008. Or perhaps he simply had more trouble locating it in addition to a loss in movement. But it’s pretty apparent that his slider lost some bite after his rookie season.

Granted, it’s really tough to gauge a real sense of progression or decline from these numbers since he bounced between starter and reliever each year. I think it’s reasonable to expect his numbers to regress in his second season with the league getting more looks at him, as well as the increase in work load as a full time starter. But there’s no denying that Joba’s slider was among the best in the league in 2008, and he’s yet to duplicate his success with it since.