At this time last season, Vance Worley was pitching in AAA, and it wouldn’t be until mid-June that his major league rotation spot was solidified. From there on out, Worley far exceeded initial expectations, putting together a rookie campaign that would have been award-worthy had it not been for the two studs at the back of the Braves’ bullpen. His shiny 3.01 ERA sat nicely with a 3.32 FIP in 25 outings.
In his injury-shortened 2012 season, Worley has seen ups and downs. But in terms of both approach and results, not much has drastically changed: his strikeout rate, walk rate, ERA, and pitch selection mimic his 2011 figures. One thing that doesn’t match as neatly, however, is home runs.
Preventing the long ball was a significant part of Worley’s success in 2011. His 0.66 HR/9 significantly outpaced the league average of 0.94, and his HR/FB rate—a metric that often varies randomly—wasn’t absurdly low enough to suggest inevitable regression. But come 2012, Worley has struggled mightily in this area. An ugly 1.31 HR/9 ranks the bottom 20% of all major league starters, and only one other starting pitcher has a worse HR to flyball ratio (21.2%!). Is there an identifiable cause to this issue?
Right off the bat, it should be made clear that plain old luck has certainly played a considerable role. Not even the most home run-sucespitible pitchers come close to touching a 21% HR/FB rate over the course of a full year. Beyond that, there are still some other potential factors that are worth looking into.
In terms of pitch selection, Worley is the same man that he was last year, throwing a healthy diet of four-seam fastballs, sinkers, and sliders among a few curves and changeups:
Whereas pitch selection has remained relatively constant, pitch outcomes have not. Home runs per flyball/line drive have surged from 2.9% all the way to 12.5% on Worley’s four-seam fastball. While not as extreme, that figure has increased for his other pitches as well. It’s important to note that his flyball rate has dropped from last season’s 37% to 26%, and this is head-scratchingly paired with an increase in home run rate. All of this seems to suggest Worley has induced less weak, lazy flyballs and more hard-hit ones.
Ignoring splits in this situation would be heedless, but unfortunately it appears that they seem to provide little insight. Worley has been particularly worse against RHB in terms of home runs this year, and this is no different than what we’ve seen from him in the past.
|vs RBH||vs LHB||vs RBH||vs LHB|
While most avenues of explanation have been exhausted, pitch location remains. It is likely that his ballooned home run rate is due to some poor pitches left over the plate. Whether or not it’s the occasional mistake that’s hurt him or a systematic location problem, we can’t really know in just 8 starts. Looking at heat maps, I did see marginal differences in overall pitch locations between this year and 2011, but none were really worth mentioning.
With only 48 innings of work to draw conclusions from, it’s hard to make any sort of diagnosis for Worley. At this point in the season, it is nearly impossible for him to match the aggregate home run-preventing numbers he posted last year, but it’s not too late for him to improve. Whether that improvement could come from weaker flyballs, hitting his spots, luck, or consistent health, it won’t really matter. Worley has shown he can be a key cog in the rotation and his 2011 level of production would be more than welcomed on the last place Philadelphia Phillies.