When it comes to fastballs, pitchers who blow smoke reign supreme. The harder you throw, the better your results. Batters missed about 27% of the time that they swung at a fastball thrown 98 MPH or harder last year. By contrast, hitters whiffed at less than half that rate against fastballs lobbed under 90 MPH. But what happens when hitters don't swing? It looks like power pitchers are actually at a disadvantage compared to their soft-tossing brethren. The harder you throw, the smaller your strike zone from the umpire.
Here's a look at the called strike rate on fastballs taken in the strike zone and out of the zone, broken down by pitch velocity. Compared to flame-throwers, pitchers who can't bust through a sheet of Bounty with their fastballs get more calls on pitches taken both inside and outside of the strike zone:
Called strike rate on fastballs taken by the hitter, by velocity
It looks like hitters aren't the only ones who have some difficulty handling premium velocity. Big Blue correctly calls about 84% of fastballs taken in the strike zone when pitchers sit near the Barry Zito side of the velocity spectrum, but that drops to about 75% when pitchers unleash Aroldis Chapman-level gas. Though power pitchers still get a good number of calls on pitches thrown away to left-handed hitters (inside to righty batters), their strike zone shrinks everywhere else. They get no love on pitches thrown inside to lefty batters, and their vertical strike zone gets chopped down to Pedroia-sized proportions.
Called strike rate on 86-88 MPH fastballs taken by the hitter
Called strike rate on 89-91 MPH fastballs taken by the hitter
Called strike rate on 92-94 MPH fastballs taken by the hitter
Called strike rate on 95-97 MPH fastballs taken by the hitter
Called strike rate on 98+ MPH fastballs taken by the hitter
Power fastballs are still preferable, even if they do garner fewer called strikes on pitches taken. For example, batters slugged nearly 200 points higher against Zito-esque fastballs last year (.504 against 86-88 MPH fastballs) than they did against Chapman-quality heat (.307 against 98+ MPH fastballs). And hitters do swing at power fastballs more often (51.4% against 98 MPH+ heaters) than slower offerings (40.3% against 86-88 MPH ), so the impact of the lower called strike rate is lessened.
That said, this info suggests that even the world's best judges of balls and strikes have their physical limitations. Umpires, like hitters, have less time to process and react as the radar gun readings increase. When near-triple-digit pitches are screaming toward home plate, it's harder for umps to make those fine calls on the edges of the dish.
Hitters might want to take more hacks against the Zitos of the world, knowing that pitchers of that ilk enjoy a more generous strike zone. Against Chapman, though? Just keep the bat on your shoulder and hope for the best.