it's interesting...on offense, we need to show patience and let guys develop...therefore we don't need to do much since these players will get better.
Yet, we have a number impressive rookie performers on defense and yet there is no cosideration that they will develop. (Johnson, Ebukum, Littleton). The thought is we need to go out and get a lot of guys. I agree with your premise about getting better on the supporting cast. However, this defense is not far from being solid. Like with Fisher defenses, this team seemed to give up a big run in many games. That is what needs to stop.
I think you find a run stopper, a big LB and, as I always say, get a CB every year. I would like the LB to step in an start...whether through FA or the draft.
Offensively, I would like to see depth on the OL and a play making TE. Keep our receivers for another year. My view is to give Goff more help...he needs that over the middle guy. Imagine this team with a 60 reception TE. The OL got through the season with few injuries. I don't think we can count on that again. Those guys are found in the middle rounds and in tier 2-3 free agents.
The big challenge is the front office and keeping the guys we have. I think it can and will be done.
We don't need wholesale changes (not saying you are saying to do this)...we need to plug a few areas and provide support to the starters.