Miggy is one of my favorite players and I watch him extensively.
Nobody has mentioned yet, that he lost like 15-20 lbs in the offseason and is in the best shape of his career. Watching him play this year, he looks very, very strong. I've heard the announcers say at least 3 times this year how almost any hitter wouldn't have been able to hit certain pitches he is hitting out of the park.
Also, like somebody else said, believe it or not Miggy has not had one his hot streaks yet either. Believe me you will realize when he does, he'll hit 3 or 4 hrs in a week, and if/when he does that he'll be on his way to a 40hr pace. I'm not saying he will def. hit 40hrs, but I have a feeling he has a real good shot of getting there this year, and in that lineup just sick back and enjoy his production.
With that said, I don't get how you said you are trying to justify playing him at 1b. He could hit 20hrs and be well worth starting at 1b. He's a 1st rounder for a reason, baring injury, the guy is almost a lock to hit .315-30-120, don't think about it anymore and don't worry about just the hr category he is a monster in every other category also, excluding sbs.