It's without a doubt the worst that I've seen in my lifetime but my boxing knowledge is limited to the early 80's to present. Have there been worse?
Not the worst ever but it's definitely at the lowest level of grading when it comes to assessing chin durability. But I don't even think it's his biggest weakness his ring IQ and his defence because of that were even worse than his chin.
One of the worst of all time no question. Not only did Khan get KOd, he was brutally KOd. To say nothing of his many other visits to the canvas, getting rocked by light-hitters etc.
There are plenty of guys who had great amateur careers and not-so-good pro careers. Khan did ok, he was good and had an average career. His best weight was 140. At 147 he was too small for the weight. He was not as physically strong as his peers so when he was hurt he did not know how to hold. In addition, he did not have 1 punch power like Klitschko to keep fighters away. Because if your chin is average like Klitschko you better have serious power to keep your opponents away but he did not have that. The problem is Khan was also too big for 140. So he could not make 140 but yet was too small for 147. This is the same thing that happened to Broner when he moved up to 140, just was too small to be good at 147 but very good when a lower weight.
An average career? f****** hell. He was a lot better than average. He was world class for a time. He was vulnerable sure, that chin was weak but considering that he's done well he had blazing hand speed and a proper fighters heart. Agrred at 147 he didn't have enough stopping power but wins Kotelnik, Paulie, Maidana, Alexander, Collazo all fighters who competed at the top of their division for a time. Even the version of Zab he faced was still decent. 2 time belt holder. An exciting fighter, with a few serious flaws that stopped going to that next bracket but a career he can be proud off.
Considering his physical and mental limitations (could not really be taught or overcome his muscle memory patterns) he EXCELLED and was very successful. I mean his last two fights he cleared over $20m
I've seen some truly disgusting chins in my time and countless instances of hideous punch resistance, but hands down the worst chin I've ever suffered the gross misfortune of laying eyes upon is the one attached to the neck of Roy Jones Jr. I kid you not there are literally thousands of species of birds with thicker craniums and better punch resistance than him. And I've never seen anyone whether it be in a boozer, a boxing ring, or on the cobbles sparked out cold from an innocuous love tap like he was by plodder Glen Johnson who is clearly at least 15-20 years older than his listed age. And that includes from sucker punches too. He's been put to sleep for a lifetime on both his front and back for goodness sake. Twice for the former. Fast asleep on his face body completely motionless like he's been taken out with a headshot from behind by a sniper.
It's up there or down there with worst chins in history. It's incredible in many ways how shaky his chin is