Except, not every person coming out of Tristar is a world-beater. Same goes for Jackson's or AKA, or any of the top-level gyms.
I'm not saying they don't help, I'm just saying that the gym itself isn't the answer. A lot of what makes GSP great is GSP. His work ethic, his attention to detail, his desire to make sure that he seeks out the absolute best treatment for his injuries and takes the time to properly recover, and his natural physical gifts. You take any one of us and put us through the same training and we still wouldn't be as good as GSP.
I'd put money on a GSP that only trained in the small, local gyms over most of the average joes that train in the top camps.