I get what you are saying - the game has evolved - but it's been a bit different and in different way. The biggest difference has really been on the OL and DL where the size has gone up dramatically. Our OL for the 1992 championship season were mostly in the 280 range and none would play today at those sizes. Our LBs in 1992 were comparable to the guys from the 2017 team (Oden Morris and Rodgers played ILB and were all 225-235, Hall who played strongside and in that scheme played both like a traditional OLB and the Star today was 235, London played outside like our Jack and was 245-250 ), but not quite as big as when we had Rolando and Donta a few years ago, but neither rolando nor donta would have been a DE in 1992 either - not big enough. The only LB spot on today's roster that is bigger is OLB, where we tend to play those guys like DEs with a hand in the dirt so they are mostly up above 250 (with exceptions like T Williams)
Basically I think what you are saying was true of football about 5-6 years ago, but in a pretty rapid manner the game has evolved again, toward somewhat smaller, faster players at some positions like LB and DL. It's created a need for 'new' positions like the Star (which plays neither like a pure CB or a pure S) or the 'weak-safety ' position that Mark Barron now plays in the NFL which is a hybrid LB/S. The OL size have increased dramatically and speed there has stayed relatively constant.
