Hefney did not play that bad he was out there trying to be superman, maybe to a fault, because everyone else was blowing their assignments. However, we did not look slow to me just stupid. I have several tackling drills I used in college for newby rugby players that Chavis needs to run. One, all players should be put on their knees and then have the entire team run full speed at them one by one. The player either learns how to tackle or gets killed. If tackling properly a 5'9'' guy can tackle a 6'5'' monster without injury.
Second, there is something called a lane. UT players seem unfamiliar with this theory. This is mostly a maturity thing guys just have to study film and grasp it is a team that he has help coming. Further, the body cannot go where the chest is not pointing i.e. do not look at the ball or feet or head of the guy you are tackling the chest tells the whole story. If each guy takes his lane and is disciplined speed and juking becomes irrelevant. Trying to kill the guy on every hit made us look stupid but not slow.
Lastly, All of the above has to be natural not hesitant. It has to be instinct. Otherwise, Hefney ends up all over the field trying to make up for all the missed tackles and coverage.