Ever since ESPN started using their computerized K-Zone in baseball games to show balls and strikes, I’ve been hopeful that one day pitch-tracking systems would completely replace human umpires. Stupid, stupid human umpires.
However, as gratifying as that would be, Ben Lindbergh says it’s not that simple:
For one thing, PITCHf/x still has hiccups. Occasionally, an error will cause the system to outright miss a pitch, which would be a crippling problem if PITCHf/x were entrusted with sole responsibility for calling balls and strikes. Granted, this is very rare — according to Cory Schwartz, vice-president of stats at MLBAM, PITCHf/x tracked all but 892 of the 709,917 pitches thrown this season (a 99.87 percent success rate). Many of those omissions are concentrated in a small sample of games affected by hardware errors, while the others (usually no more than one per game) are attributable to glare or other adverse lighting. As infrequent as they are, though, the potential for missing pitches would require some fail-safe for a computerized system. “Do human umpires miss pitches? Sure,” says Dan Brooks, founder of PITCHf/x repository BrooksBaseball.net. “But for the most part, they don’t just forget pitches happened. It’s not like everybody is waiting for the call and they’re just like, ‘I didn’t see that one, guys.'”
And as much as I hate the fact that every umpire has his own quirky interpretation of the strike zone, the rule book really doesn’t allow for computer-like precision:
The east-west direction is relatively easy, since the horizontal dimensions of the rulebook strike zone don’t shift from at-bat to at-bat. “You could do that right now, with the existing technology,” says Harry Pavlidis, director of technology at Baseball Prospectus and founder of PITCH Info LLC, which provides consulting services to teams. “On 98 percent of the pitches, that would work.”
But determining the top and bottom boundaries of the strike zone is much more difficult, both because batter heights and stances vary (from batter to batter and, to a lesser extent, for the same batter within a season) and because the rulebook description of where the zone extends — from “the bottom of the knees” to “a horizontal line at the midpoint between the top of the shoulders and the top of the uniform pants” — is open to interpretation. Even if a computer could identify that midpoint, how could it pick the moment at which “the batter is prepared to swing at a pitched ball,” the rulebook’s equally vague prescription for when the dimensions are supposed to be set?