Two years ago, Chuck Liddell’s considerable cranial real estate -- mowed into a Mohawk, landscaped with kanji tattoos -- was synonymous with the UFC. More importantly, synonymous with the idea of an upstart combat sport that was more dynamic, more dangerous and subsequently more engrossing than boxing.

Jack Dempsey, Joe Louis: These were straight guys, your grandfather’s idea of a badass. Liddell looked like a video game thug, and fought like one, too: predictable patterns of movement, trademark moves -- watch the overhand right -- and beatable only with considerable practice and a faultless attack.

In a sport in which belts frequently have the turnover rate of a McDonald’s, Liddell stayed on top for an auspiciously long time. He was undefeated from late 2003 until mid-2007, largely avoiding the suspense of any outcome other than an opponent lying crushed at his feet. He was rarely victimized, partied hard and mumbled his way through pioneering endorsement deals: Warner Bros., Dell, Nyquil.

But what made Liddell so good at being an assailant -- a planted, aggressive stance, a good chin, peerless takedown defense courtesy of a hydraulic core -- also made him predictable. Quinton Jackson sent a hook postmarked for his jaw before Liddell could even retract a body shot. Rashad Evans commented that he telegraphed his violence with his facial expressions, a handicap that might be OK in “Punch-Out” but has more severe consequences in real life.

Liddell is a performance car slowly running out of gas. But considering his next race is against a jalopy, he might have enough left in him to finish some laps.

Since entering the UFC in the fall of 2007, Mauricio “Shogun” Rua has undergone one of the more curious transformations in athletics. Previously an inexhaustible bundle of aggression, stomping on faces as if he were putting out a fire, Rua turned meek virtually overnight. Against Forrest Griffin, he was smothered, tired out and eventually submitted. Against Mark Coleman, he looked as though he had finished a triathlon only minutes before the show. (Fortunately, the 45-year-old Coleman looked as if he had a lung removed, so things balanced out nicely.)

To gain any real measure of Liddell’s current abilities, he would probably need to face someone with fewer question marks. The Rua he faces Saturday at UFC 97 is not the terror from Japan, but an air-sucking impersonator. Dana White has instructed Liddell to “dazzle” him. If Rua’s conditioning issues persist, Liddell is going to make like a strobe light.

And if not? If Rua delivers the third brutal finish in Liddell’s last five fights? It calls into question -- and a fair one, I believe -- of taking into consideration an athlete’s sustained damage when granting them licensure. The NFL’s demanding schedule and suck-it-up attitude has spawned a small but disturbing trend of retired players who suffered multiple concussions in their careers and went on to a retirement of forgotten appointments, lost car keys and substantial cognitive impairment.

I’m not an MD, but I doubt JAMA is going to take any issue with this statement: Getting bashed in the head isn’t good for your health.

It likely doesn’t bother Liddell. It shouldn’t: He’s a fighter with the necessary pride and ego to do what he does for a living and not turn into a simpering mess on fight night. But it should bother commissions charged with his safety.

Not that they’re the sole authority on his health. Personal responsibility is still the sport’s first defense against unconsciousness, and Liddell is doing a lot of the right things. He’s trained with American Top Team to open his game, re-install a threat of wrestling and add to his armory. He undoubtedly has power -- it’s often the last thing to go -- and a probable desire to erase the lingering distaste of his recent defeats.

The problem is, the right things may come after too many years of doing the wrong things. Never having shadowed Liddell in his nocturnal element, I can’t speculate on what he’s done to decompress from his day job. But Liddell himself -- or more accurately, his ghostwriter -- has written in his autobiography of wild nights that re-define decadence. The grimy TMZ.com also has a Chuck Liddell page, much of which consists of Liddell preparing to test his cardio conditioning against another gender.

Hedonism is a young man’s game; so is fighting. You can occasionally break one mold or the other, but you can’t take on both and expect to come out with anything less than one hell of a hangover.

And if Liddell has a cure, he needs to mix it up on Saturday. In more ways than one.

For comments, e-mail jrossen@sherdog.com