Ironically, Sinfosky was the driving force behind Windows 8, the company's attempt to reclaim lost relevance in the personal computing world. Unlike previous versions of Microsoft's ( MSFT ) operating system, Windows 8 encompasses PCs, tablets and phones. It required the various divisions of the Redmond-based tech giant to work together. (The company is notorious for the opposite -- if you haven't seen it before, check out the satirical take on its organizational chart here .) But Sinfosky was a polarizing figure at Microsoft. He had an impressive track record for delivering software on time but was known for his combative style. For Windows 8 -- the future of Microsoft -- to succeed, the company's various factions need to continue to collaborate, not compete. Current CEO Ballmer alluded to this need in a release issued by the company on Monday, saying he is "grateful for the many years of work that Steven has contributed to the company," but adding that it is now "imperative that we continue to drive alignment across all Microsoft teams, and have more integrated and rapid development cycles for our offerings." Sinofsky seemed the most logical future successor to Ballmer. After all, he knew the business inside and out and had developed a loyal group of followers at the company. But if Microsoft's future is all about driving alignment within the company and faster software updates, the former Windows head didn't have the necessary profile. His departure presents an opportunity for Microsoft to cultivate leaders that