I haven't seen him play, but the reasoning is that Law thinks any offensive utility that Kozma provides is smoke and mirrors. But Jackson can draw walks and is, apparently, a good defender.

Shortstop is crazy thin everywhere. It's why the pretend prospect-for-prospect trade between the Cards and Rangers of Oscar Tavares for Jurickson Profar got so much discussion that one or the other GMs actually commented on whether they'd do it.