Maybe.

Kupp is not the same player. I don't know if its something that he needs another off season to correct, or if he has some permanent damage.

I guarantee the Rams FO knows the answer to this, and how they draft and operate in FA might just be the tell. If they use a high pick on a WR or pick up a FA like Tee Higgins, it probably means they know that Kupp's play is permanently diminished, whether he retires or not.