Brian Wilson’s Two-Seamer

Early in the season Eno Sarris introduced us to Brian Wilson’s flithy two-seam fastball, a pitch Wilson claims to have added this year. Sarris’s GIF showed Jamey Carroll flailing wildly at Wilson’s newest offering. Wilson, 29, already had three years as a solid closer for the the San Francisco Giants, so the idea of him adding another nasty pitch is intriguing. With over half the season books and Wilson effective again this year — though his peripherals have taken a step back — I wanted to check in on that two-seamer.

First off here is evidence that Wilson is, in fact, throwing a pitch that he didn’t last year.

Wilson’s two-seam fastball, like almost all others, has less ‘rise’ and more tail than his four-seam fastball. It is about the same speed as his four-seam fastball, both average 94mph. Although I don’t think he threw it in 2010, it is not a completely new pitch. He threw a handful of two-seam fastballs in 2009. But this year he is throwing lots more: so far he has thrown 27% four-seam fastballs, 28% two-seam fastballs, and 45% sliders and cutters. I think — based on media reports and what Wilson says — that the slider and cutter are two distinct pitches, but I am not 100% confident in disentangling them with the Pitch F/X data.

So how is Wilson’s two-seam fastball doing? Interestingly the pitch has been very easy to make contact off of: just five swinging strikes off 84 swings on 225 two-seamers. That is a swinging strike rate of just 2% per pitch and under 6% per swing, compared to 16 swinging strikes off 74 swings on 213 four-seam fastballs (7.5% per pitch and 22% per swing), and 36 swinging strikes off 149 swings on 360 sliders and cutters (10% per swing and 24% per swing). For a 94mph fastball from a guy with nasty stuff the two-seam fastball has been been surprisingly easy to make contact with — especially given how nasty the pitch looked in Eno’s post. But the news isn’t all bad, the pitch does get lots of grounders (58%) and weak contact (just .289 slugging on contact).

So the two-seamer adds an interesting weapon to WIlson’s arsenal: a pitch to go to when he needs a weak contact or a ground-ball out. But unlike his other pitches it is not a swing-and-miss offering. And I think his reliance on the pitch (he is throwing it over a quarter of the time), could be responsible for his career low 7% swinging strike rate (a big drop from last year’s 10.1%) and consequently his lowest, though still great, strikeout rate since 2007.