Matt over at Aesopian.com is a jiu-jitsu nerd. That is not an insult by any means. Anyone who blogs about jiu-jitsu is likely a jiu-jitsu nerd, and anyone who reads jiu-jitsu blogs is likely a jiu-jitsu nerd as well. There's plenty of nerding out going on this sport, and it often yields interesting insights. Matt's latest obsession has been an analysis of any major competition DVD that he can get his hands on. He takes notes on each match, which at the black belt level can be horrifically boring, and tallies successfully executed techniques. Currently, he's working his way through the 2009 ADCC, but he completed annotating the 2004 Mundials not too long ago, and the data reveals some notable trends. Click these links for the quick and dirty summary of the takedowns, sweeps, submissions, and guard passes that fighters landed in the 2004 Mundials.
Based on Matt's notes, there are four techniques that you should think more about when structuring your training.

