Yes, someone like Wade Phillips can attract former players to the Rams and be a better fit for his defense.
It’s clear they will address it through a combination of in-house players and draft picks, but personally I don’t expect a big free agent signing. Having said that, 2-3 Denver defenders who played for Wade are UFAs this year, though, only 1 is a backer and 2 of them were on IR in 2017. Still if they have recovered and can play having been on IR could just make them cheap. It’s not just LB they have to address, it’s CB and NT too, so signing a Denver player or 2 on the cheap would help.
I think them trying to sign Tru is a giveaway that they would use the 1st rounder on an edge rusher. I’ve heard it said many times that Wade can come up with ILBs out of lower picks, and that he wants the money/higher picks on the outside. Though Tru wasn’t signed before because he was asking too much, so who knows.
This reminds me of the defensive rebuild in 2000. They promoted some guys (like Little), made a trade, signed a couple of guys, and drafted some guys (though not all that effectively I thought), and the result was good. They have a good core to build around in Peters, Joyner, J.Johnson, Donald, and Brockers, plus some depth that may or may not include a potential starter (like Littleton obviously).