Doesn't matter whether a play is made on it or not, and it depends on the height of the ball (used to be 10 feet). The key here would be the reaction of the umpire. If he/she doesn't immediately announce "infield fly rule" or something similar, the players may assume that it is a playable ball. Kind of like "fair or foul". An ump is only supposed to verbally announce a foul ball, while visually signifying a fair ball. If the players hear no announcement of "foul ball", they are to assume that it is "fair".