It's been said that Denver (Elway mainly) LOVES Rosen
If I were them I'd focus on keeping the team they already have up to snuff. Their O-line could use a piece, Demaryius is 30, Talib is 32 and CJ Anderson is injury prone. Those guys are still good players at this stage of their careers but I'd start trying to find young guys that can reinvigorate those positions. If you trade for Rosen you potentially lose that ability and you create a salary blockade at QB.
Granted I do think Semen has some trade value. Damn shame what happened to Lynch.