Watch replays closely and you'll see that Holbrook, the left field umpire, watches as shortstop Pete Kozma backpedals into left field. As soon as Kozma waves his arms to communicate that he's ready to catch the ball, Holbrook raises his arm to signal an infield fly.
In other words, the umpire waits until he's certain it's a play the infielder can make. Kozma apparently thought it was a play he could make.
Whatever caused him to suddenly peel off — was it when, amid the stadium noise, Holbrook accompanied his signal with a verbal call of "infield fly?" — Kozma suddenly changed direction, as infielders are taught to do when they believe they hear the outfielder calling that he can make the catch.
October 6, 2012
Paul White says yes.