Help me understand how teams run up the middle with this much success

It's not one position though. ANY great Gator defense had studs at linebacker. 06 may have been the "weakest" but that defense had Reggie Nelson locking down the back half of field, really solid corner play, Siler holding down the middle and yes, a truly stout defensive line from end to end.

 

True, we have to have studs all over the defense and LBs are a big part of that. But it all starts up front. The bigger, badder, stronger the D-lineman are the more freedom/movement the linebackers will have to clean up the QB or the running backs.