I think you are right. The buddy of mine who introduced me to my current BJJ dojo was a heavy weight high school wrestler and was one of the top guys on his squad. I believe he 21 now.
When he joined BJJ, the dude went from blue to purple in less than a year and won, I think three first places in the local BJJ tournaments at blue belt, at that time. The guy's spider guard is amazing. 2 and 1/2 years to purple is really, really good.