Everyone goes on about chucks heavy hands and yes he certainly has heavy hands and knows how to use them (ouch). However no1 mentions that he didnt have them when he first joined the UFC. For eg vs Noe Hernandez and vs Horn even vs Paul Jones.
Now i am NOT saying he wasnt a good fighter back then, just that Noe had alot more power than him and he didnt have NEARLY the power he has now. So to say it cant be learnt, well Chuck is a great example of someone who has developed it.