His Fenway ERA is 6.04, in six games (four of which were starts). Only one of those games came within the last three years however, which he won. His peripherals look great in any case, which indicates to me the ERA is a result of bad luck and small sample size. In any case, 25 innings, many of which came his first three years as an Oriole, are hardly an indicator of the future. So you're right, its not the fairest way to look at it.
Keep in mind these don't include the postseason. Against the Yankees, he's pitched 8 games, 9 IP, with a 4.00 ERA. That includes a 3:10 BB/K ratio, which is good. You'd want better, but that an indication that he's not getting murdered out there.