This is going to be unpopular, and this is in no way an endorsement of the DTs on the roster nor the team philosophy about addressing the position, but the issues with the run defense are less about defending the inside run, and more about properly setting the edge on off tackle runs.
The ends are more concerned with getting upfield and creating havoc on the pass rush, and frequently blow their contain/edge setting responsibilities. This happened time and time again on Sunday. Fowler, Armstrong and Lawrence all allowed chunk runs to their sides by abandoning their outside leverage and slanting hard inside. The other issue has been the defense running a big nickel constantly, and sacrificing a LB for playing Kearse/Wilson in that role. It helps with covering TEs, and has enhanced blitz opportunities against the pass, but they have a hard time holding up in the running game.
If the ends can play better with their eyes rather than blindly charging inside off the snap, the run defense will be much improved. To what extent that affects the pass rush would be the resulting question.