He obviously trained extensively in the grappling arts but, like others have said, he was not a home grown wrestler out of the gate. Fighters like Cormier, Jones, Hendricks, etc. came from wrestling families, did well in high school, junior college, and/or even went to the highest levels in college, etc. before training MMA. GSP obviously saw the importance of setting up a good TD attempt and maintaining top control. The way he strikes just completed the package.
So while a lot of other MMA fighters who either came in with a striking or wrestling background and offset their weaknesses by learning striking or grappling defense, GSP invested more time and skill learning how to set up and secure TDs and maintain top position. Instead of a defensive wrestling mindset, he developed and offensive grappling mind set while still maintaining a striking base. It says a lot about the ideology and psychology of GSP. GSP obviously can grapple defensively that just comes with the trade, but it never really mattered nor was he tested there often because his offense was his defense. How are you gonna takedown someone trying to dart in and take you down? It's a conundrum at least that's probably what his more credentialed grappling adversaries thought.
