It's official: Mark Pincus is stepping aside as CEO of Zynga. It's hardly surprising: Founders rarely make good public-company CEOs.

Mark Pincus has left the building.

Well, sort of. In a statement issued earlier today, Pincus, the founder and CEO of Zynga, the troubled gaming start-up that's been struggling to maintain its relevance ever since its IPO in December 2011, announced he's fired himself, and hired another industry veteran--Don Mattrick, a former head of Microsoft's Xbox division--as his replacement.

"As I reflect on the past six years, I realize that I’ve had the greatest impact working as an entrepreneur with product teams, developing games that could entertain and connect millions," Pincus wrote .

"I've always said to Bing and our Board that if I could find someone who could do a better job as our CEO I'd do all I could to recruit and bring that person in.…