You can be a great DC, OC, ST coach... but you still need the players.
I think Shula did a nice job with what he had. Didn't have the talent to be the number 1 defense. And I don't know this but I feel like maybe some of there smoke and mirrors that worked earlier were seen through later. The right answer, imo, is to improve the talent on the defense... and the glaring suspect is CB talent.
Personally I would hope to find an excellent CB in free agency... maybe two. And then focus on the defense in the draft (picking up a few CB's in the draft regardless of what happens in free agency)... keeping the needs of the offense in mind. And to me the needs of the offense is a WR... like Boston... I like them all but I think he fits what the Rams want to do. I admit that Lemon looks like a star. And since I think the Rams will double down on ST this year, he could be the guy. Killing a few birds. (Although, I like X Smith a lot and wish he could find a larger role in the offense)
After CB and WR... I think OL... then I think the needs even out.