Just to pick one category: the Rams were the worst team in the league in opponents yards per carry at 5.1. At the same time they lead the league in QB pressures. It just seems that bringing a weakness from worst in the league to middle of the pack (or better) would help the team more than getting better in an area where they already lead the league.
That being said, I honestly believe the Rams will improve in edge rushing as well as run defense, RZ efficiency, and 4th down defense this year so the point is probably moot.
AlbaNY_Ram