I don't want to say "it doesn't matter." But in my opinion Wade's defenses are predicated in (1) pressuring the QB and (2) generating turnovers. And if they do that but give up 150 yards rushing along the way, well so be it... We have all read some of the "stop the run on the way to the QB" stuff and I think there is truth to that. And that's fine. It is just not a philosophy at all of "stop the run first." And to some extent I suppose that's the NFL today.
And again to me run defense is basically about two things- discipline and effort. While Suh added value he took a lot of plays (or games?) off, and then we saw his impact in the postseason when he flipped the switch. No one is going to say players like Gaines are anywhere close to Suh, but could having a big, strong, plugger in there on running downs that has a really high motor make a difference in the run game? It could.
And I do think that, while both Littleton and Barron each have a lot of strengths, run defense isn't among them, especially with both not having a lot of size. That was a recipe for poor run defense which is why hopefully Kiser and (situationally) Matthews may produce somewhat better teamed with Littleton.