As someone who grew up playing baseball and shifted to an all grass infield mid-(amateur)career, I would argue that an all grass infield is by far the best for an infielder. If they really cared about bad hops, they'd just shift to that with or without the field transformation concern. It's a truer bounce, hands down. Would there eventually be an impact in the base path? I don't know. Maybe in the course of 81 home games, it would be. I never played more than 25 or so games on one field like that. I never saw an issue, in college or even high school, with base paths becoming problematic. Still could happen, but I doubt it.
I tend to agree with those who see the players as making preemptive excuses. It's a sad commentary on how far the Yankees have fallen with their big money busts.