The easiest way to think of it for me is to think of players who fit each role perfectly:
Joey/Nick Bosa - Dana Stubblefield - Bryant Young - Charles Haley
But to your point, Saleh comes from a different version of Seifert's defense. Aside from adopting W9 full time, his 3 tech is a monster at 325 pounds and 6'5"+. Usually that's for a smaller interior rusher who wins on quickness by shooting gaps.
He does seem to lean on the bull rush a lot (AA, Jones, Buckner, Bosa, etc.) but I think that's because of his bigger-is-better philosophy.
PS: Courtesy of DonnieDarko, here's Kyle talking about why he liked the Seattle defense (originally Seifert's), now Saleh's version from Jacksonville...the foundation BUT he noted it constantly needs to evolve, hence adding W9 full time and with Woods, adding more 2 S shells, etc. Let's see how it evolves more this year. More dime? More man? More base?
[ Edited by NCommand on Jul 24, 2020 at 4:48 AM ]