I'm not so much concerned about the bat as I am his throwing ability. His fielding is fantastic, but if he's going to have a ton of throwing errors due to shoulder issues, he can't stay there. Especially if Rendon is raking in the minors. I don't want to see him forced to move to first, but we can't let homerism blind us to obvious problems.
Why don't you want to see him at first? Someone did a comparison, and when healthy, Zimmerman's bat is perfectly in line with 1B production. I think he would be an elite defender at 1st as well.
