From BR Bullpen

A pop-up or pop fly is a fly ball that is hit with an almost vertical trajectory. A pop-up will usually land in the infield or in foul territory not far from home plate.

Pop-ups are very easy to field, except in very windy conditions or when there is confusion among a team's fielders. Because pop-ups are considered to be virtually automatic outs, baseball's most complex rule, the infield fly rule was devised to prevent teams on defense from benefitting unduly from pop-ups hit by their opponents by turning cheap double plays.

Preferable, a pop-up should be caught by one of the four infielders and not by the pitcher of catcher, because pitchers are not selected on the basis of their fielding ability, and because catchers are facing the wrong way when a pop-up is hit, making it harder to judge the ball's flight path. There are some exceptions, however. Gary Carter, for one, wanted to catch every pop-up hit in his vicinity, and almost never misplayed one; other catchers are much more tentative and can turn the most routine pop-up into an adventure.

Further Reading[edit]

  • Anthony Castrovince: "The complicated relationship between pitchers and popups", mlb.com, May 5, 2023. [1]