Why is the Office of Special Counsel Investigating Rove?

I couldn't figure this out for a while. The OSC director, Scott Bloch is hardly a paragon of integrity. He hires cronies and and has publically opined that gay federal employees have no protection against discrimination. So, why all of a sudden has he acquired the honor (and the balls) to take on Karl Rove?

The answer, according to David Corn in The Nation, is that Bloch is under investigation himself. The investigation is Bloch's self-preservation act. I would not be surprised if Rove and Bloch have drinks after work.

I investigate you, you investigate me, and we both keep our jobs.