Blair Westlake, Microsoft’s vice president for Media and Entertainment has resigned, saying that the company’s recent reorganization and mission don’t fit his “expertise or skill sets.”

Westlake confirmed that he’d left the company to Variety today, just one week after he’d been a main fixture at the company’s off-site showroom at this year’s Consumer Electronics Show in Las Vegas.

On the surface it seems that Microsoft owes Westlake’s departure to its reorganization and a possible internal decision to explore digital entertainment in a different way than it had previously with Westlake telling Variety that:

“Over the last few months Microsoft has been undergoing a large-scale reorganization. During that period, I have had the privilege of working with numerous talented and professional people. While I will miss their company and our interaction, I truly believe that this move is in the best interest of all parties concerned.”

Why Westlake made the decision to leave is key since he appears to have been one of the executives responsible for pushing the Xbox into new entertainment categories outside of games. He oversaw Microsoft’s relationships and licensing agreements for television shows and movies, and had been with Microsoft for 10 years. Before that he’d worked at Universal Studios and Universal Television & Networks.

Microsoft recently hired Nancy Tellum to lead Microsoft Entertainment Studios, a new internal content production outfit. Whether that project’s direction convinced Westlake to leave is unknown. However, Microsoft did make waves went it formally announced that it would produce its own content for Xbox Live as well as offer entertainment produced by other companies to Xbox Live users.

Microsoft has commented on who will replace Westlake.