I don't put much stock in Romney's record in Mass.His legislature was 85% Democrat, meaning he had about as much actual power as the queen of England - none. The Dems could pass anything they wanted and overriding Romney's vetoes was just a formality. And he did veto (literally) hundreds of pieces of legislation. In that situation a person has to decide whether he wants any political influence at all or just sit at his desk and pout for 4 years. He wisely chose the former.
Inversely take a guy like Rick Perry. As governor of Texas he had a stellar record as a conservative, but how could he not? When he started railing against Romney's "vulture capitalism" he lost me for good.