You have to be under it to catch the ball you freaking idiot.
But that has nothing to do with the call
"An INFIELD FLY is a fair fly ball (not including a line drive nor an attempted bunt) which can be caught by an infielder with ordinary effort, when first and second, or first, second and third bases are occupied, before two are out. The pitcher, catcher and any outfielder who stations himself in the infield on the play shall be considered infielders for the purpose of this rule.
When it seems apparent that a batted ball will be an Infield Fly, the umpire shall immediately declare Infield Fly for the benefit of the runners"
You don't have to be "under it" when the call is made.
Oh and after watching the replay, he was under it. He had come to a stop and was looking directly up.