Boetsch is a good fighter but he's on a run of extraordinary circumstance. I thought he beat Lombard, but it was clear that Lightning wasn't himself on that night at all, whether he was injured, had nerves, or whatever. If the Hector that showed up against Palhares showed up against Boetsch, Boetsch would have been on the losing end.
That being said, I think Boetsch can beat Costa. He's got a good chin, underrated grappling, and really solid power in his hands.