This article was dead on. Those guys didn't have the aggression to consistently finish their blocks. You frequently saw them in the vicinity of RB's being tackled just standing there watching the play.
Compare that to Mizzou's OL that had a fraction of the natural ability and athleticism... but ALOT of that mean streak. They were flat out nasty at times as a group. Almost always on their blocks a half count after the whistle. Their RB's knew that and could anticipate their cuts because of it.
Some of that is the players' innate mental/emotional disposition and personality. Part of it is coaching.