Middlebrooks is going to give you these waves. He is not a patient hitter, so all of his offensive punch will be in the hits (or lack thereof). But clearly the power is there, and since his demotion, his mechanics have been simpler. Swing is a more compact, lower half is not as busy.
We'll have to live with the fluctuations at the plate, but there is no reason he can't be an above average defensive 3B who gives power and below average sort of On Base. That is a solid starter.