It may be hard to believe, considering that this is Mixed Martial Arts and such, but if one champion had to be considered the most difficult champion to defeat in his own weight class, and the discussion called for anyone besides Anderson Silva, one would have to bring up Jon Jones' name.
You might not like the guy and there's also a good chance that anyone looking at his mug right now wants to punch him in the face, but you can't deny Jones' ability to not only defeat high-level fighters after taking a punch, but also defeat high-level fighters and still manage to make said "high-level fighters" look less impressive than they actually are.
Let's recap for a minute:
First, after submitting Ryan Bader and earning a title shot, Jones made Mauricio "Shogun" Rua look worse in three rounds than Shogun has ever looked in his entire career.
Then, he took shots from Quinton "Rampage" Jackson that would have knocked any other foe of Jackson out. Keep in mind, the same shots Jackson landed on Jones might actually knock Ryan Bader out at UFC 144.
Now, we're fully aware of Jones' title win and first defense, but it starts to make things even more frightening once we get to Lyoto "The Dragon" Machida, who so far is the only title challenger to have taken the first round away from Jones. But what happened in Round 2 with Lyoto?
He took a left hook, got dropped and got choked into unconsciousness via a power guillotine from Jones.
The scariest part about it is that there are at least three UFC light heavyweights that can definitely still challenge Jones.
Dan Henderson can load up his right hand to drop Jones, Phil Davis can take Jones down and potentially keep him there and Rashad Evans can do both if he puts it all together, though he probably couldn't knock Bones out the way Hendo could.
Still, consider the way he made Machida pass out and remember that even the people who picked Jones to beat Machida admit that Lyoto was no slouch either.
If Machida could look as he did after Bones handled him, what does anyone really think that Henderson, Davis or Evans could do once Jones meets them inside of the Octagon?
It's tough to fathom, but if Jones has anything to say about it, it'll be even tougher to watch.