Coaching DLine really isn't that difficult.
You mostly just teach hand fighting & leverage techniques.
The most difficult aspect of it is getting 270-300+ guys to understand situational & assignment football. Being discipline against the run & understanding gap responsibilities.
But most of what DL's do is stuff you can't teach. It's a raw strength & effort position. You either have it or you don't. You can be the best Coach in the world, but if a kid isn't internally motivated it won't matter how much you teach & how many tricks of the trade you give him.
I honestly believe it's more a recruiter position than anything. If you recruit via HS & Portal elite DL's, the rest is up to the S&C program & the player themselves.
Trust & believe, there's no secret formula that Larry Johnson or Mike Elston, or Tray Scott teaches that every other DL Coach doesn't teach or have access to; its as simple as, the programs who consistently recruit the biggest freak of nature athletes at DT & DE, consistently have the best Defensive lines.
Back before NIL, it was more prudent for us to find a real DL guru so to speak, in order to supplement for the fact we could never land top tier DLineman. But now in the open free agency market it's a whole lot easier & simpler; Spend the money to get the best players.
If you don't wanna spend what it takes to get the best DL's, then you live with the results.