Swilling I felt was a product of being around a bunch of good LB's like City Champ and Sam Mills. Your free to disagree with me but when Pat went to Detroit and then later Oakland he was not the same player. He did not have the people he had here to help him. Rickey Jackson had a bit more success in San Fran because he had a good defense already their anyway. As far as the thread goes, the big difference is size and technique. Back then the game was not nearly as complicated as it is now. DE's are bigger, faster, and required to be more durable now then in the early 90's.
Offenses are more complicated now too, OC's are smarter and teams have more difficult schemes to understand. So the animal has changed quite a bit to make a good comparison