I came accross this a few weeks ago on youtube, and it's on a different thread right now. Mack isn't the most agile dude in the world or the best pass blocker, and he looks downright awkward at times. But what he is is a straight up mauler with size, strength, intensity, and intelligence. Here's the proof, and boy could we use a guy like this in the pivot:
http://www.youtube.com/watch?v=P8xCkToEnJ8
http://www.youtube.com/watch?v=P8xCkToEnJ8