With the Braves trailing the Cardinals 6-3 in the bottom of the eighth inning, and with runners on first and second and one out, Atlanta shortstop Andrelton Simmons hit a pop up into shallow left field that both shortstop Pete Kozma and left fielder Matt Holliday chased after. The ball fell between Kozma and Holliday, and it looked like the Braves would have the bases loaded with one out for Brian McCann...but the play was called an infield fly, and Simmons was ruled out.
The infield fly rule is notoriously tricky, but this call met none of the criteria for the play. The ball wasn't in the infield, it was pretty clearly in the shallow outfield. The rule says that an infielder can catch the ball with minimal effort, but Kozma was backpedaling on the play and didn't have a good read on the ball the entire time. Thirdly, the call must be made reltaively quickly. Left field umpire Sam Holbrook made the call as the ball was already nearing the ground, a criminally late application of the call.
So to summarize: late call, and a bad call. McCann would walk to load the bases before Michael Bourn struck out to make the inning-ending second out.