And its why even at the level he is playing at right now, I doubt he would have been able to win the SB in 21' with the Rams. They had no running game and an above average OL at best in terms of pass blocking, but again not a good run blocking group.
He would not have been able to pull those last 3 playoff games out nor some of those games down the stretch of the regular season.
Stafford was the right move and the trade benefitted both teams. Now maybe McVay/Snead could have built a super team around him eventually, but Donald, Whit, Ramsey, and probably Kupp would have never gotten a ring with him.