He is from the OKC area, graduated high school the same year I did, and is among the greatest wrestling talents my state ever produced (Danny Hodge is by far the greatest, but Hendricks is definitely up there in the same class). He won three state high school championships (which is no small feat, high school wrestling here is as competitive as high school football in Texas), three Big 12 wrestling championships, two NCAA wrestling championships, and was a four time NCAA All-American.
His rise in the sport of MMA was kinda meteoric, he had the one loss to Rick Story, and didn't lose again until the GSP fight, a fight the majority felt he won. Then after losing the rematch to Robbie, he fell off a cliff. Based on what I know of Oklahoma HS wrestling, I have no doubts that he'd been using PEDs since at least that point, all of the wrestlers at my own high school used them, you almost had to if you wanted to be competitive in wrestling here. My school's team was successful in 6A, the same class that Hendricks' school competed in, in which Hendricks was the best the state produced at the time. His decline in MMA coincided with the advent of USADA in the UFC, so the many on this site through the years that had noted as much were probably correct about his nosedive. Wouldn't doubt if it was a combo of no longer being able to have a competitive advantage mixed with fatigue from cutting weight since at least junior high, and maybe elementary school.