The only thing Wilson has over Stafford is his mobility. Both have exceptional arms and accuracy, particularly at long range. Both are different types of QB's. Stafford is the prototypical old school type of pocket QB. Tall, strong-armed pocket passer which may have gone out of vogue in recent years, but whose style has been proven by Brady to be still dangerous when protected. Wilson has been forced to make off scheduled throws simply because of the poor o-line he plays behind.
Give Stafford protection and he's equally dangerous who is able to get to the line early and make his own reads and adjustments. Both play in different systems and in McVay's system he has a QB who looks to be a perfect fit. Wilson has been the model of consistency in terms of stats but to pass a comparison judgement vs Stafford is an eye roller. Because of the differences in the teams they played with it's impossible to make definitive comparisons. By that token Goff more than held his own playing the Sea Hawks. Stafford is also a tall pocket passer who without a doubt is a huge upgrade over Goff. To expect him to play the SeaHawks better than Goff would seem more than reasonable considering the current Rams on both sides of the ball.
People overlook that football is a team game and that has to be taken into context when comparing QBs. Stafford on the Rams with their offensive talent, and a defense that should limit the opposition is an imposing prospect to the rest of the NFCW. The Rams FO obviously felt that the missing piece preventing the winning of a Lombardi was a QB. Goff put up 3952 yds and 20 TDs last year, so to think Stafford could put up 5K yds and over 30 TDs in 17 games isn't a stretch. Stafford makes this team deadly, because with Akers running the ball against a box that isn't stacked the Rams look to be able to control the clock in most games.
Until proven otherwise the Rams look to be the cream of the NFCW which in turn is the toughest division in the NFL.