In John Manuel's chat today, he had some nice things to say about J.D. Martinez.
I like Martinez because I think he'll hit and hit for power — 7 of his 11 hits so far are for extra bases. It wouldn't shock me if he wound up approximating Hunter Pence's offensive numbers other than SB, and he plays with similar energy. He doesn't run like Pence though and isn't as well-rounded of a player, but I think he's the best of the young position players the Astros have called up so far.