Haye ruptured his Achilles tendon, it's a horror injury.
As far as the "Hayemaker" goes, I box (only for fitness, but I spar weekly with lads who do compete mainly white collar) I have done for several years now, your power comes from not your arms but up through your feet, your legs and your core. If you plant your feet and transfer energy it's that much harder a punch, watch a hook in slow motion. It's from planted feet the front which should be up on your toes, should swivel as if putting out a fag as you swing in, you push in the direction of the punch and then to use the term "sit down" on it. The force comes from your base up through your core and out through your arm. Your arms just swinging aren't as strong as when you move as one, it's why most don't get knocked out with jabs, and when they do it's mainly a leaping forward jab in which a persons full weight is behind it. Watch top quality boxers their feet are just as important as their hands.
Haye has legit KO power, he did rattle Bellew in rnd 2 or 3 when he caught him, credit to Bellew his chin held up, but being dismissive of a man with proven KO power when he's on one leg is incorrect. From round 6 onwards i'd say Haye was hitting at as little as 50-60% of his potential, If you don't believe me go to one of them punch things at an arcade smack it a few times then try doing it without putting weight on your feet, you'll see a difference.
The rest of your analysis is also wrong, Haye won round 10 on one leg, he also comfortably won round 5 and was pissing round 6 until his injury, i'm assuming you watched it in the pub? have you rewatched it sober? I've watched it twice and as I said above:
Round 1 is 50/50 Haye wasn't settled, Bellew threw a few descent counter punches but nothing of any note, Haye was the aggressor
Haye then won rnd 2,3,4,5 and in 6 bellew only got a knock down by bumping into him because Haye is hoping on one leg as he'd been injured.
7,8,9 are Bellew but it's because Haye is literally standing on one leg swinging.
11 the ending if you watch it Bellew misses every shot and belly flops Haye out the ring. Haye on one leg can hardly get up, his corner chuck in the towel although he did make the count comfortably.