José Iglesias Swings Too Much. Or Too Little. It's Complicated.
May 6, 2021 There’s no one way to hit well, but there is one constant in hitting: batters swing too often. The intuition behind that fact isn’t hard to get to: if you swing at a pitch outside the zone, you’re taking a ball and turning it into weak contact (it’s hard to hit pitches outside the zone with authority) or a strike — that’s bad! If you swing at a pitch in the zone, you’re turning a strike into either a strike (if you miss) or contact. Swinging is so bad outside of the zone that it overwhelms the advantages of hacking in it.
Source: fangraphs.com