On the upgrade thing, I do think it is. Hard to rank it exactly but if you go from the 20th best QB in the league (which Goff has basically been the past two years) to the 12th (which is Stafford) you're doing pretty well especially considering the importance of the position. Can Stafford be
better than 12th in the Rams' environment? Maybe. But even if not it's a sizeable upgrade.
I will bet he will have digested half the offense by the time the deal is official in mid-March. Rams other needs on offense don't change- upgrade at center, find a deep threat WR4 and find a very good blocking TE. Do those 3 things and I think the offense is set up very, very well.