It isn't a surprise that it was incompetence, and it isn't a surprise that he was only worried about targeting Democrats.

But it wouldn't have been a surprise to me that it was corruption either. The only surprise would have been "a complete vindication", which isn't possible given the fact that Sandusky was a pedophile.

He didn't want the story to break in the middle of the 2010 election season. Maybe not "corruption" but pretty shrewd. It's catching up to him now. This is why even every Republican I know will not support Corbett.

"Those questions include a decision not to execute a search warrant on Jerry Sandusky's home until June 2011, more than two years after Fisher's complaints first reached the Attorney General's office in March 2009. By that time, Corbett was governor, and he had been succeeded as Attorney General by his appointed replacement, Linda Kelly. Sandusky wasn't arrested until November 2011.

(The search yielded, among other items, lists of Second Mile program participants with annotations by Sandusky about kids he appeared to have a personal interest in.)

There is also a focus, some noted, on a five-month period in 2010, the year of the gubernatorial campaign, in which the case did not significantly move forward. At the beginning of that period, in April 2010, at least one of the state prosecutors working the case, Jonelle Eshbach, raised the possibility of pressing charges based on Fisher's statements alone, the sources said.

That suggestion was ultimately dismissed by Eshbach's superiors, but only after lingering for several months."

They're not exactly mutually exclusive. I think it's both, but the AG couldn't fully prove motive.