[greymule]

Said it was an association thing.

Now there's an intelligent answer.

Odd how many umps think runners have to tag up on an uncaught infield fly, though. I worked with one ump who defined when they needed to tag as the moment the ump called IFR. So if the ump calls IFR at the peak of the popup, that constitutes a catch and the runners can tag and go. Then if the ball is caught while the runners are already standing on the next base, they have still properly tagged up.