Nailed it. Your shots from 2019 show a Polanco whose swing looked more like Nellie's, with the bat held more vertical, and a shorter path to the ball with a tighter snap and a more explosive swing that gets you just as high an average, plus it lifts the ball more, getting more HR's and balls banging off walls. Polanco 2020's swing looks longer and flatter, more like a conventional infielder trying to hit line drives and keep his average up. Problem is, that kind of swing makes it very hard to get any snap on an off-speed pitch that gets you on your front foot. See how Cruz does it? He steps forward, yet still keeps the bat pointed upwards, saving the snap, which he knows he can do in an instant. Even when he's fooled, Cruz can still hit the ball a long way with that late snap, off his front foot. Polanco can't do that because he's uncoiling as part of his initial forward movement. Weak ground balls if he's out front. You don't see a lot of those from Cruz.