Gray and Hamels have identical 6.9 f-WAR 2014-15 to date.
Love Gray--that's why brought up the subject--but, for me, an established Ace at Hamels age, with no history of arm problems, is at least as good a bet for excellence in next 4 years as a guy with a two-year history in majors--especially an unusually small starting pitcher like Gray.
Think there is a tendency to assume, at first glance, that a young guy has a long run with club he's with now. But, in the modern free agent era, here today, gone in free agency. Think have to think of both guys as same years of control. Once you get into that reality, you might re-think differently.
Also, Hamels has been pitching in worst situation possible in 2015. Bad ballclub, bad defense behind him, and constant intensive, trade hangover for over a year as he takes mound.