Super Bowl 50: Peyton Manning, Cam Newton present different challenges for offensive linemenSix-time Pro Bowl center Matt Birk discusses the difference between blocking for a mobile quarterback and blocking for a conventional, pocket-passingSI Staff|Share on FacebookShare on XAdd us as a preferred sourceSix-time Pro Bowl center Matt Birk discusses the difference between blocking for a mobile quarterback and blocking for a conventional, pocket-passing quarterback.Add us as a preferred source on GoogleFollowLoading recommendations... Please wait while we load personalized content recommendationsPublished Jan 28, 2016 | Modified Jan 28, 2016SI STAFFShare on FacebookShare on XHome/NFL