When the Pop-Ups Fell In
Is a pop-up the same as a strikeout? No, of course not, by definition they are very different things. A pop-up requires contact, whereas a strikeout requires no contact, or at least very little contact, or a two-strike foul bunt. Pop-ups and strikeouts look nothing alike, to the eye. However, to the numbers, pop-ups and strikeouts look very much alike. On one level they are very different, and on another level they are very similar.
A few weeks ago, Dave asked whether infield flies should be included in FIP. The idea is that IFFBs have little to do with defensive skill, and pop-ups are effectively strikeouts, in terms of plate-appearance result. Pop-ups don’t advance runners, and pop-ups are almost always outs. They’re not literally always outs, but then, a batter can reach on a strikeout if the ball gets away from the catcher. So while pop-ups lead to outs slightly less often, they’re still just about automatic.

