I think it depends on when you're holding your draft versus when we find out how bad his injury really is. The half-dozen rankings I've seen rate him as high as 31st overall to as low as 81st overall player, and average out to 62nd overall. If you want to really reach for him, late 4th. I wouldn't consider him a value pick until at least the 7th.
As a life-long Twins fan, I love Mauer. But I'm not that high on him from a fantasy standpoint. He'll get you the high BA, but he has limited power, won't get you steals, and really doesn't produce that many runs or RBIs. I'd recommend passing on Mauer, and getting someone like Iannetta several rounds later. Good luck!
C-Mauer, 1B-Fielder, 2B-Kinsler, SS-Zobrist, 3B-M. Cabrera
OF-Beltran, Markakis, Crawford
UTIL/Bench-Vlad, Damon, J. Reyes
SP-Billingsley, Oswalt, King Felix, Shields, Wandy, Carpenter, Edwin Jackson, B. Webb
RP-Nathan, F. Francisco, B. Wilson, Street