An improved offensive line will help the running game, but with McCarthy and Dak, this is a passing-based offense. The running game is simply complimentary. But they should still call a lot of play action and make them respect the run a bit.
So, the defensive trenches is wayyyy more of a concern to me than RB. If they can't stop the run, this defense is going to struggle against the more physical teams, and there's quite a bit of them on the schedule. And of course, no hint of a deep playoff run if the trenches aren't secured. The front 7 (including the LBs), they're going to have to take a big step this year, or we'll just see the same results in the playoffs...no matter the regular season record.