Tree was above average but only due to his range and ability to drop in coverage. That is, btw, extremely valuable nowadays, but he does need to work on his ability to take on blocks and/or beat them on the interior.
ILB is going to be the most interesting part of watching what Wade does with our defense. His scheme puts a lot of emphasis on ILB fills and beating of blocks in the run game, particularly if the NT is a guy who one gaps. This is why I expect the Rams to bring in a two gap run stuffer at NT and play Brock 5T. It will ease things a bit on Tree and Barron or whomever else is the other interior LB.
And re: Barron, he really struggled this year. Could be that some of the mistakes I thought I saw weren't him, but I'm pretty comfortable with the opinion that he was the source of some significant run gashes the defense suffered. He's a really tough dude, and can be an impact player around the LOS, but it's gonna be interesting to see what Wade does to squeeze the most from him. I suspect either him or Tree will end up doing some rushing on the outside, where they can make plays in space.
So IMO a NT and ILB will be added to this defense in some combination of FA and the draft. Good thing is neither of those positions are pricey on the FA market, so they may elect to do that right out the gate.