|CC Sabathia has been good thus far, but his velocity remains an issue. (USATSI)|
Something is different about Yankees pitcher CC Sabathia. To open the year, Sabathia's fastball velocity has been down significantly. After averaging 93.04 mph with the pitch last year, Sabathia's velocity has dropped to 90.59 mph this April. The 32-year-old has already done a tremendous job getting by with a diminished fastball and will look to continue the trend against the Blue Jays on Saturday. Through five starts, he has a 3.34 ERA and 3.60 FIP. Those numbers don't indicate a struggling pitcher. But given Sabathia's age, workload and recent elbow surgery, the drop in velocity is alarming.
Diminished velocity seems like it would have a big impact on performance, but is that actually the case? With the development of pitch tracking systems, we can go back and look at how pitchers performed after experiencing a significant loss of velocity to open a season. From 2003 to 2011, there have been 95 starting pitchers who have seen their velocity drop by at least 1.5 mph in April. Of those 95, 59 percent saw declines in both their ERA and fielding independent pitching (FIP). Pitchers who experienced at least 1.5 mph decline in their fastballs tended to see their ERA increase by about .26, a little more than a quarter of a run. They saw their FIP increase by .20.*
While that amount of decline isn't going to immediately ruin Sabathia, it is significant. If we apply those numbers to his stats from last season, Sabathia would finish 2013 with a 3.59 ERA and a 3.80 FIP. Those numbers are still solid for an average pitcher but represent decline for Sabathia.
That shouldn't come as a huge surprise. FanGraphs.com's Bill Petti and Jeff Zimmerman have done some SABR award winning studies on pitcher aging curves, which show Sabathia is at a prime age for velocity loss. In their first article on the subject, they provided this chart:
The black line, or the one that ends up at the bottom of the chart, represents velocity. By age-32, pitchers have already seen steady decline in their velocity. This also is the case with Sabathia. According to BrooksBaseball.net, Sabathia's fastball averaged close to 95 mph as recently as 2011. It dropped to 93.04 last season and now sits at 90.59 mph.
We also know that velocity tends to improve as the season progresses. But in Sabathia's case, that might not matter as much. To cite Jeff Zimmerman again, he found velocity tends to stabilize after three starts for pitchers coming off the disabled list. While Sabathia was never actually on the DL, he is coming off elbow surgery. Even if Sabathia is able to gain 1 mph with his fastball, which was the margin for error in Zimmerman's article, he would still be throwing at a significantly reduced rate.
Sabathia has overcome velocity issues in the past but never to this extent. Given the elite level of performance Sabathia has shown in the past, he can still be an incredibly effective pitcher even if he declines at the average rate. While Sabathia should still post above-average numbers this season, it's unclear what will happen in future seasons. Research shows that velocity loss continues as a player gets older, and this will likely be something that Sabathia has to deal with for the rest of his career. Sabathia has shown an ability to deal with velocity loss early this season. But it's going to become increasing difficult to overcome as he ages.
* Given my math skills, these should be viewed as rough calculations.
*Huge h/t to Bill Petti, who provided database research for this article.