Brock Lesnar became World champ within just 1 year and 3 fights after giving MMA a go when he failed to cut it in the NFL.
Guys like Brendan Schaub and Travis Browne, failed athletes from other sports who had no combat sports/martial arts experience prior to taking up MMA in their mid-twenties, became top contenders in the UFC within just a couple of years.
You've just seen a 30 odd year-old nightclub bouncer, new to the sport, who can't even throw 20 punches without gassing out, get hyped as the next big thing and given a title shot.
There are some good athletes in the lower weight classes but the heavyweights are very, very poor. It's real bottom of the barrel level stuff. Now I'm not saying that random NFL players could just waltz into MMA and beat anyone right off the bat, obviously they couldn't. But the idea that elite level athletes would need years and years of training to at least be able to compete in the HW division is clearly not true.
I get the impression that a lot of sherdoggers and MMA fans are like Joe Rogan in that they don't really watch much sport outside of MMA/UFC so they don't understand the true level of what it is they are watching. MMA heavyweights are sill much closer in talent and athleticism to guys from the early days like Tank Abbott than they are to top draw large athletes from other sports like football, basketball, boxing and rugby.