Sure, but he probably doesn't face the other teams #5 all that often throughout the season.
Make the adjustment and see how he compares to other 5's -i know you can do that.

Off hand, I would take Lohse, Wily Peralta, or Fiers over him from Milwaukee.
Pick one of them - they can't all be 5th starters- if they are then they got a team of 5th starters and I would take my chances in a pennant race against that team.