Let's see, since Timlin is generally coming in after Myers and Bradford it stands that he is allowing their baserunners to score, doesn't it? And, I assert that ERA doesn't mean that much any more. What does matter is who gets on base when you come it, how many you can strike out per nine innings and if you can keep the ball in the park. Timlin doesn't give up the long ball I grant you but the inherited runners thing is a real problem.
Don't get me wrong, I've seen Bradford from his old days in Oakland and he was very good at what he did. He just hasn't been all that effective in Boston so far.
Relievers are not become magical creatures who can prevent all hits when they have runners on base. Most of inherited runner results are luck and the situations a reliever is put in; some of it is strikeouts and popups.