The ump may have thought the SS was getting out of the way of the ball with intent to cause a force out, and then raised his hand. Honestly it looked like Kozma (who?) had the ball lined up the whole way until the very end, so I can see that aspect of it. I think the timing of the call is the biggest issue, because otherwise the play falls comfortably within the rules' description of what an infield fly is. It "should be called immediately," as the rule states, but does that mean it can't be called after a few seconds but before the ball hits the ground? That part of the rule is rather vague; i.e., it doesn't say it must be called immediately. And even if it were an egregiously blown call -- which, quite frankly, it isn't -- it does not even remotely begin to justify the disgraceful behavior of the Braves' fans.