I get the guys you are referencing, and yes they all made Lovies defense go from a scheme to elite, but just a disruptive DT that can shoot the gap can make this thing go. Yes, Urlacher was a HoF and Tillmon elite at taking the ball away. But Lovies defense at its best was when Tommie Harris was crazy good upfront. Get pressure up front like that, and mistakes will happen. Mistakes happen and the D can score, or you get quick turn opportunities from the offense. Then you can let a competent QB take some shots.
That's true, and I agree with your analysis. But the single greatest difference between the college game and NFL game from the perspective of how a coach spends his time is recruiting. Lovie didn't have to expend a lot of energy to get the likes of Urlacher, Briggs, Harris, Tillman, Mike Brown, etc. And while disparities exist, the talent level across the NFL is fairly even.
Now, Lovie's defense -- in conference play at least -- is going up against offenses that are almost always bigger, faster, and more talented. He has to close that gap via recruiting, plain and simple. We have no equivalent of Tommie Harris. We don't have a Nic Bosa or a Devin Bush or a Micah Parsons. Defensive guys that can change a game. Heck, I'd settle for "average" talent across the board, but we're not even there yet.
So Lovie's defensive success in the NFL, IMO, will have little bearing on his tenure here unless he recruits at a higher level.