Fister’s Flummoxing Fastball

Another eight solid innings for Doug Fister last night brings him up to 55 pitched in just eight starts in 2010. With his ERA still under 2, but his xFIP (4.23) essentially matching his xFIP from a year ago (4.50), I wanted to dig into his pitch numbers to see if there is anything substantially different in his process this season.

The reason for the low ERA is easy to souse out. Fister’s BABIP is just .231, his home run per fly ball stands at 1.8% and his LOB% is 79.1%. The first two are obviously unsustainable and the LOB% might be realistic if he struck out a batter per inning, but given that he’s at less than half that rate, I wouldn’t bank on it holding up. Granted, Fister has allowed fewer line drives this season so his lower BABIP is not entirely a result of great defense, but it’s far too early to call that a repeatable skill.

Doug Fister has almost an identical strikeout to walk ratio this year (2.5) as last year (2.4), but only because both strikeouts and walks have declined by a nearly equal percentage. The main change is an 11-point increase in his ground ball rate. That is a significant leap and worth finding out the cause for.

I created a table of all of Doug Fister’s pitches from each of 2009 and 2010 and compared how each pitch has generated swinging strikes (to predict strikeouts), balls (to predict walks) and ground balls (to predict home runs). The conclusion I can draw is that Fister is somehow getting far more ground balls from his primary fastball in 2010 (49%) than he did previously (26%). Doing so has allowed him to throw it much more often and he has thrown his fastball nearly 80% of the time in 2010 from 61% in 2009.

I can only find that as a clear difference. Fister is missing fewer bats, but that is to be expected when he throws fewer breaking pitches and more fastballs. Ditto for issuing fewer walks. Fister appears to have added some deception to his delivery that has increased his ability to get batters to take fastball for strikes and hit more of them on the ground when they do swing.

What change that is and whether it actually exists rather than a statistical sample issue is the purview of scouts. I cannot tell if Doug Fister is a different pitcher this season, but his numbers so far do exhibit some suggestive trends.

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Matthew Carruth is a software engineer who has been fascinated with baseball statistics since age five. When not dissecting baseball, he is watching hockey or playing soccer.