Wilson cut his teeth and his reputation by using his legs. If he stays in the pocket, he struggles to see over the line. If you look at his spray chart he threw either deep or short to the sidelines, but seldom over the middle. With his quick feet Russell escaped the pass rush with his patented spin move, giving WRs time to get deep. Wilson's deep ball was a thing of beauty. With his legs he often took off on QB options. Defenses had to take that into account as well. I've watched Wilson's leg become increasingly less effective the last two years. His skill set does not allow him to be effective standing in the pocket. He needs to move around to buy time, but his legs are letting him down.
No question a latissimus dorsi tear can effect his throwing velocity and accuracy, but it has no impact on his decision making, which has been poor last year in Seattle and this year in Denver. I agree with a poster above that Wilson is probably a top 15 QB. I think that is likely where he'll finish in fantasy, but many considered him elite. If you accept the fact that his legs are critical to his success, then you must accept the fact that he is a descending talent, both in real life and in fantasy.