My take...
People are remembering the Stevie that had a hell of a great connection with Fitz. Those two connected well. With EJ, that connection wasn't there, in my opinion. I wonder if SJ requires a certain type of connection with his QB that doesn't fit EJ's game. He is a "draw it in the sand" type of receiver, that can be tough for certain systems.
After reading the reports from this off-season, I was shocked that SJ wasn't working with EJ. I don't thing they mesh well, and Whaley and Marrone recognized it and got some value, and added younger players that can grow with him.
I love the Watkins trade, he is a stud. We completely upgraded at receiver no doubt.
Good luck SJ, it was fun, but without Fitz, I think you are very average.