Statistically, he‘s a little above average. When you count efficiency and longevity together, he’s in a spot where maybe he has a case, but it’s not like he’s near the best of his generation.
There’s no way “he’s in” right now. In 2012, Joe Flacco would have had a better claim of “he’s in” than Stafford right now. Stafford is a 1X pro bowler, 0x all-pro, career sub-.500 quarterback. The Super Bowl is a huge boost for him, but it’s possible a player is “good,” wins a championship, and falls short of Hall of Fame territory. Let’s say theoretically a guy like Vinny Testaverde won a championship with the Jets in 1998. Is he a Hall of Famer? He would have a similar claim as Stafford, based on his stats adjusted for era.