While the general mood around Sean Mannion's fit with the Eagles is great, this NFL Insider noted his fit remains a mystery. “This is the most significant change the Eagles' offense has undergone since Sirianni has been their coach. Sean Mannion’s bringing a new system, a new style of offense. Sean Mannion, a very inexperienced coach, he's only been at it for three years, has never been a coordinator or called plays before. Until the live bullets start to fly, it really is a mystery, Eagles fans.