He's not a HR hitter, he's had serious back issues (ie not conducive to swinging as hard as you can for 5 minutes, sitting down, and repeating).
He'd probably be best served taking the whole Allstar break off, but to do the HR derby and play in the game the next day seems like a ridiculous thing for him to do.
I can't beleive the Twins are ok with this.
Joe Mauer-C-Twins Jul. 10 - 4:24 pm et
Joe Mauer, who is having a career year, has agreed to participate in the Home Run Derby.
Too bad it isn't a line drive derby; Mauer would win for sure. He's at a cool .389/.461/.651 this season.