Swinging Out of the Zone and Really Swinging Out of the Zone
A few years ago — unfortunately I don’t remember where — I remember seeing an article beginning with the premise that not all pitches out of the strike zone are alike. What we offer here on FanGraphs is O-Swing%, a rate of swings at pitches out of the PITCHf/x zone. Yet this groups all such swings and pitches together, and for a hitter, swinging at a pitch an inch outside is different from swinging at a pitch a foot outside. One might indicate a little better discipline than the other. The author decided to see if there were cases where O-Swing% was misleading, given the distribution of swings at balls. What he found was, no, it’s fine. Over full seasons, there’s no need to get more granular. But what about when you’re short of full seasons?
This little study was inspired by Jose Abreu, and a hunch. Abreu, right now, owns a 152 wRC+ in his first-ever exposure to the bigs, and his isolated slugging percentage is an impossible .369. He’s already been everything the White Sox could’ve dreamed of. Abreu also owns one of baseball’s higher O-Swing% rates, at 39%. He’s been fed a lot of pitches out of the zone, and he’s swung at a lot of pitches out of the zone, and that trait and success don’t always go hand in hand. What I wondered was: has Abreu been swinging at borderline balls, or has he really been fishing? He’s already demonstrated that he can drive pitches on any of the edges. His functional zone might just be bigger than the average zone. To what degree has his zone really expanded?