PHILADELPHIA — The Eagles’ tepid passing game gets most of the headlines, but the once historic running game is the bigger hurdle en route to overall offensive efficiency under new offensive coordinator Sean Mannion. When the Eagles rewarded Saquon Barkley with a proactive two-year, $41.2 million extension in March of 2025 – making the superstar running back the highest-paid in NFL history with $36 million fully guaranteed — it felt unnecessary.  Fresh off the greatest rushing season in NFL history (2,504 rushing yards through a Super Bowl LIX championship while earning NFL Offensive Player of the Year honors), the stipend seemed like a thank you more than a projection on Barkley moving forward. That said, it’s fair to surmise that the Eagles did regard Barkley as one of the cornerstones for a perennial contender. Fast-forward to the end of a disappointing 2025 regular season, and the numbers on the back of Barkley's trading card revealed a declining player.…