The true powerhouse backfield of Bettis, Culver, Tony Brooks and at times, Ryan Mihalko, was one that every opposing team hated. Bettis was an absolute beast at 247 lbs, Culver was a ironclad tank at 220 lbs (and one of the strongest guys pound for pound), and had been an excellent fullback in 1990. Tony Brooks was playing at a pretty cut 220 lbs as well.
Some folks may discount Ryan "Hulk" Mihalko for being one of the slowest backs, but the man was incredibly strong, and could deliver crushing blocks. Lou even used him as a nose tackle at times.
Regardless of who was getting the ball in the triple house backfield, someone was going to pay a terrible price for trying to make the tackle.