Its not as simple as just looking at the stats, it never has been. The play of the entire team can be impacted. Just as an example, imagine how much motivation the OL has when Dwayne Haskins is back there doing Dwayne Haskins things, holding the ball too long, taking sacks and throwing to the wrong guys. Imagine the WRs not running full proper routes because they know Haskins won't find them. Then imagine the confidence they all have with AS under center? Improved QB play improves the entire team, and while AS may not have been Peyton Mannning,
he was the best QB they had under center in many years,.... for much of the roster the best QB they had for their entire tenure in DC. The defense also may have played better, because maybe they knew AS would not throw the game away in the 4th qtr like Haskins or Mark Sanchez or Case Keenum was doing week in/week out. Heck we even saw how the whole team rallied around Taylor Heineke instead of Carson Wentz, so its also true they rallied around AS instead of Keenum or Allen or Haskins. This seems strikingly obvious and you also need to compare AS's stats on the same team as those other bums.
If Alex Smith had not gotten his leg destroyed, he absolutely would have been worth that trade and that contract, without a doubt. So again, it was bad luck, not a bad trade.
11-5 under Dan Snyder, Jay Gruden and RR, should actually put him in the Hall of Fame