If the Eagles were going to choose a first-time play caller as their new offensive coordinator, Sean Mannion was the guy. “I’m thrilled to have Sean Mannion on board as the new offensive coordinator of the Philadelphia Eagles,” head coach Nick Sirianni said in a team statement Thursday. Zac Taylor, the head coach in Cincinnati, beloved by Joe Burrow, was Mannion’s QB coach for a season with the Rams. And Klint Kubiak, now the offensive coordinator for the Super Bowl-destined Seahawks, mentored him in Minneapolis. All those names and legacies sound sparkling and fantastic, but Mannion has yet to prove himself as an offensive coordinator.