Overview
A fly ball is a batted ball that travels in a high arc through the air, broadly categorized as infield flies (pop-ups) and outfield flies. Infield flies are almost always caught for outs and rank among the least productive batting outcomes. Outfield flies are also caught if within a fielder's range, but clear the fence for home runs. The value of fly balls was fundamentally reassessed during MLB's 'fly-ball revolution' of the 2010s. Data analysis revealed that hard-hit balls launched at angles between 25 and 35 degrees have the highest probability of becoming extra-base hits, prompting many hitters to deliberately retool their swings to elevate the ball. The result was a surge in home runs accompanied by a parallel increase in strikeouts. NPB has felt the fly-ball revolution's influence, though differences in ballpark dimensions and the official ball's characteristics have tempered the effect compared to MLB. Fly balls also carry tactical value through the sacrifice fly: even when an outfield fly results in an out, a runner on third can tag up and score, earning the batter an RBI. Far from a simple binary of out or home run, the fly ball is a multifaceted batted-ball outcome whose value depends on context.