Id say defensive reactions. eg RJJ was getting tagged more in his last couple of fights than he had in his whole career. where did you get the Sanchez pic?never seen it before. very cool :good
The natural ability goes first, like the physical .. reflexes ... hand eye coordination .. response timing etc... stamina can still remaine until later life.... those things can be a part of ones drive.. you can want things to go on forever.. Your stamina can be improved by your fitness.. (fitness can be maintained for years..) age related wear and tear like reflexes etc never do.. its just part of your youth.. Punch resistance can default too..
Got to be speed and reflex. Theres 60 yr olds running the London Marathon, so i dont think stamina is a problem really. the likes of DLH never coulnt manage 12 rounds THAT well. Fighters tend to slow down altogether as they get older, hands arent as quick nor the feet and they get hit more.
The killer instint maybe,ok when your poor and wanting to make a name for yourself,but some become to rich and soft and cant then be arsed,other wise i agree about the reflexes