Rarely does a D stand totally on its own.
It needs the O to control the ball, run the clock, have VERY few 3 and outs, and a low turnover number.
Or......the O needs to score substantially and let the D hold the fort.
But the D cannot have a kind of O that the Rams had all 5 years under Fisher (and especially last year) and be a top 5. We simply don't have that kind of dominating talent across the board on D to do that.
The D needs the O in the same way the O needs the D to get up that high in the overall rankings (acknowledging that occasionally a generational O or D comes along that is so dominant it carries the game nearly by itself).
So, no, the Rams will not be a top 5 D because I can't imagine the Rams transforming the O that completely in just one year....and especially with a 2nd year QB that is more rookie than sophmore. And McVay doesn't seem to be an O coach who wants super-safe and conservative play. He is aggressive, which means that turnovers are inevitable. I think the priorities on O this year need to be 1) very few 3 and outs, 2) only rarely have losses on any down, especially 1st down, 3) cut down significantly on penalties, 4) have an O that is a balanced with both the run and pass having to at least be respected.