I remeber seeing Will Shields on one of these post season challange shows where they do position drills to compete as best whatever. Anyway, the one area he had trouble with, and said himself that it was common, was blocking the shorter sleds (translate tacklers). Problem is, when your 6-4,6-5,6-6, its hard to get your pad level down to 5-11 chest level.
I'm not saying I prefer little DT s, just that I think it's interesting how sometimes a player or coach can sometimes take advantage of a preceived shortcoming.