I think his floor is a pinch-defender type of guy. The guy you bring in as a defensive sub in the bottom of the 8th leading by one and you need good defence,
No idea what the ceiling might be, but at most it might just be a semi-competent bat to go with his amazing glove.
Miller is 4th on the team on OPS+ and the only guy who has played 1B for over 100 games. He is bad no doubt but is unfortunately one of the better hitters on the team and the only "proper" 1B.
A guy who was pretty solid? Being injured is his thing but at the plate, he has been great so far, Frelick doesn't even have the injury problems. As far as I know, his only big IL stint was the thumb issue