NEW YORK — Major League Baseball can envision a day when mechanical umpires could be tested to call balls and strikes.

Baseball has used computer systems since 2001 to evaluate ball-strike calls, and umpires responded by gradually realigning their strike zones back toward the rule-book definition.

Baseball Commissioner Rob Manfred was asked Wednesday before the NL wild-card game whether baseball may eventually use a mechanical strike zone.

“The technology of calling balls and strikes without a human being involved has continued to improve,” he said. “The principal reason that we’ve always done it after the fact is unlike the box that you see on a broadcast, our system that we use to grade our umpires, someone goes in and manually adjusts the strike zone for the batter. And there are material differences in the strike zone.”