According to today's Herald, A.J. Burnett has gone on his torrid run of late because he has finally bought into the philosophy of pitching to contact. Burnett is also crediting strong defense supporting him.
The Sentinel, on the other hand, has a different take on the matter. They credit A.J.'s success to an effective sinker. Even if you prefer the Herald's take on the matter, the Sentinel story is worth reading - if only because it provides some good technical discussion about sinkers.
While I'm not sure, and it's not like I'll be able to watch tonight's game to see it with my own eyes, I'm going to have to side with the Sentinel here. Crediting A.J.'s success to a new (or recently more effective) pitch makes a lot more sense to me.