That's why the freaks that enter into boxing don't normally do well. You get these guys who are great athletically but have no chin or good enough cardio to set the standard pace for pure striking. You can be the fastest runner, lift an ungodly amount of weight, jump the heightest, but if you have no chin, you aren't gonna do shit in pure striking...boxing speacially. What separates one great boxer from another is often intangible things that you cant train or teach like heart, mettle, skill set's, and chin. You have it or you dont. Boxing is where the money is. I've always was amazed at GSP and how gifted he was. Always wondered why someone like him with his talents didn't give boxing ago and try to go for the big bank, then I saw Serra ko him. He has no chin, but in MMA he's a great fighter, but he can hide his weakness with his wrestling. If he was to straight box, he'd be found out really quick. Pure striking is so tough to when fighting other's that have perfected the sweet science at the highest level after years of training. Key word "years" like the starting age of 5. That's very hard for a gifted person from other backgrounds to overcome. You simply can't catch up to there level. You don't enter into boxing at age 25, with great athletic attributes and expect to do well against those kids, who are men with yrs. of training under their belt.