I have seen Dick Butkus meet a big, hard charging fullback in the hole, greet him head on, stand him up in his tracks, and dump him straight over backwards and drill him into the ground.
I have seen Butkus pursue a sweep towards the sidelines, chase down the play and proceed to take the blocker, the running back, and a defensive teammate into the sidelines with him knocking over everything in his path.
Butkus could have played in the first football game ever played, or he could play now.
He was a defensive machine.