why don't they force you to catch it on an infield fly rule...if you drop it then each runner gets to advance
pretty easy double play with a runner on first and a true infield pop up , say to the pitcher, pitcher could let it drop, then throw to 2nd and 2nd baseman throws to first for a double play , when it should still be only one out on the play and the runner still on first as if the easy ball were caught, as it should be like 99.9 % of the time by MLB players.
Halfway into LF is not the infield though.
Keep in mind that the late hand signal by the ump was also accompanied by him yelling "Infield fly, runner's out" and that likely disrupted the communication between the outfielder and infielder. If as everyone says that it shouldn't have been infield fly, ump is yelling nothing and communication is not disrupted and it is 1st and 2nd with 2 outs instead of 2nd and 3rd with 2 outs. It actually may have helped the Braves.