I'm in DET and have seen all but one of his starts -- he's not a super prospect, a la Hamels, Weaver etc... He has piched very well to date. He is , however, benefitting largely from the first-time-around-the-league honeymoon and having a quality team behind him. His hit and strand to rates to date reflect a tremendous deal of luck. Remember, his AAA WHIP is around 1.5.
As a Tiger fan, I hope he remains the second coming of Pedro Martinez. But his historical skill numbers point him being more like the second coming of Pedro Astacio. Best guess? 4.25-4.50 and .500 record through the next 3 months. And I hope I'm wrong!