Forget about his lack of definition, or his height... the reason why he is special is because he is an ORGANICALLY grown HW.
So often now we have guys that come into the fight game very late. Often times it's guys that were other sports stars- basketball or football- and then they have a career ending injury and need to fight.
But, Andy Ruiz, sorta like Chris Arreola (with Arreola really being an overblown Supermiddle/LH than he should be a HW) started out boxing as a lad and grew into the system as a junior and then a senior amateur fighter.
He put the fight game down for a while and got into some other stuff.... most likely eating pork-pies.... and then he came back to the game!
His skill and pedigree is very deceptive. You think you are going in with a fat slob, while a little true, you are going in with a well polished fighter with great skill and technique.