You've heard a lot about the recent spate of upsets in mixed martial arts, which was punctuated by 4-1 underdog Houston Alexander's devastating 48-second thrashing of Keith Jardine at UFC 71.

You haven't heard as much about why these are happening.

I've chatted with several people with deep roots in MMA off the record over the past few days. Here are some of their thoughts on why more big-name fighters than ever seem to be going down to defeat:

1. The sheer number of events being run means more opportunities for more fighters. UFC ran five events per year as recently as 2004. Now they're looking at two dozen this year. If you have more than 200 matches in a year as opposed to less than fifty, there will be more upsets through sheer volume.

2. High-profile fighters can be scouted in minute detail by up-and-comers. If you're Joe Lauzon, for example, you grew up looking up to someone like Jens Pulver, watched all his fights on television, watched them over and over on DVD, and his success was a big part of the reason you got into the sport. Lauzon went into his 48-second TKO of Pulver at UFC 63 knowing all of his tendencies, strengths and weaknesses. Pulver, at best, might have seen some of Lauzon's clips kicking around on youtube. So many of these unknowns are coming in with a scouting advantage over their opponents.

3. Some of the top guys, quite simply, are getting a taste of the good life and aren't working as hard as they could to keep up with changing times. This could be the case with Mirko Cro Cop, who didn't even bother training in an octagon before his fights with Eddie Sanchez and then Gabriel Gonzaga. Cro Cop looked lost while he was trying to defend Gonzaga's elbows on the ground at UFC 70 while pushed up near the edge of the cage, right before the restart that led to Gonzaga's KO kick. Cro Cop, incidentally, has since purchased a cage for his future training.

4. Finally, perhaps the biggest factor, we're starting to get a hint of the sheer scope of how many talented athletes are getting into MMA these days. While some outlets just noticed that UFC exists last week, anyone who has been paying attention any length of time knows that interest in MMA has been steadily rising for years. What we're seeing now is the first generation of top-notch athletes who specifically got into the game wanting to be the next Matt Hughes, B.J. Penn, Fedor, Rich Franklin, etc.

Consider there are now groups like Team Takedown, which is recruiting NCAA champion wrestlers into MMA. They signed a pair of Oklahoma State standouts -- Jake Rosholt, the 2006 and 2007 national champ at 197 pounds; and Johny Hendricks, the 2005 and 2006 champ at 165 -- who will be training with Randy Couture.

With athletes of that caliber banging down the door looking to get in, don't expect the upsets to end anytime soon.

***

The idea that all the recent title fluctuation in the UFC is unprecedented simply isn't true.

Take a look at the results of title matches between UFC 46 on Jan. 31, 2004, and UFC 53 June 4, 2005:

46: B.J. Penn beats Matt Hughes for the welterweight title; Vitor Belfort beats Randy Couture for the light heavyweight title (on a fluke injury, but still a title change)

47: No title matches

48: Frank Mir beats Tim Sylvia for the vacant heavyweight title

49: Couture regains the LHW title from Belfort

50: Hughes beats Georges St. Pierre for the vacant WW title

51: Evan Tanner beats David Terrell for the vacant middleweight title; Arlovski beats Sylvia for the interim HW title after Mir had to forfeit the title due to his motorcycle accident

52: Hughes retains against Frank Trigg; Chuck Liddell beats Couture for LHW title

53: Rich Franklin beats Tanner for MW title; Arlovski retains against Justin Eilers.

From the time Penn beat Hughes to the time Franklin beat Tanner, you had eight new champions crowned in nine title fights over eight shows (one of which had no title matches), three of which were filling vacancies. In a span of more than 16 months, Hughes was the only man to step into the octagon as a UFC champion and leave with the belt.

Now, let's take a look at another eight-show span, from UFC 64-71:

64: Sean Sherk decisions Ken Florian for vacant lightweight title; Anderson Silva beats Franklin for MW title

65: Sylvia retains HW title against Jeff Monson: St. Pierre beats Hughes for WW title

66: Liddell retains LHW against Tito Ortiz

67: Silva defeated Travis Lutter in a non-title match, originally scheduled to be a title match, but Lutter missed weight.

68: Couture beat Sylvia for HW title

69: Matt Serra beats St. Pierre for WW title

70: No title matches

71: Quinton Jackson defeats Liddell for LHW title

Over this span, two champions retained; Silva won a fight which should have been a title match, and there were five new champs crowned, including a vacancy filler.

The current stretch of title changes may seem more pronounced because it has occurred over a seven-month span, but it simply has yet to match the 2004-05 run in terms of volatility.

(For a post-press conference column on the fight, CLICK HERE)

This is it, the big one, the fight which brought everyone here to the MGM Grand. Anyone who has even the slightest interest in mixed martial arts knows the story behind this: The UFC's biggest star, light heavyweight champion "The Iceman" Chuck Liddell, has lost three times in his stellar career. He has avenged his losses to Jeremy Horn and Randy Couture. Only Quinton "Rampage" Jackson remains.

Jackson (26-6) took it to Liddell (20-3) in a one-sided fight on a PRIDE show at the Tokyo Dome in 2003. But they were never able to rematch until Jackson became a part of the UFC when the company bought his contract as part of an assets sale for the struggling World Fighting Alliance late last year.

Liddell has won his past seven fights since losing to Jackson, all by the way of KO or TKO. He is the longest-reigning current champ in the UFC, holding the title since beating Couture in April, 2005. Rampage has won his past four, including his UFC debut, a second-round TKO of Marvin Eastman at UFC 67.

The fight closed on the MGM Grand books with Liddell as a -170/+150 favorite. More than 46,000 people voted in our FOXSports.com "Who will win?" poll, with 67 percent picking Chuck.

The lights go down. The noise is deafening and just about everyone in the building is standing. Memphis native Jackson's walk out to the octagon is slow and deliberate. Jackson gets a mixed reaction as he enters the octagon. He grabs the fence in his corner, looks down toward the mat, and stretches out his calves.

The lights go down again, and a huge roar comes from the crowd as Liddell makes his appearance. Liddell, who lives in Santa Barbara, CA, wastes no time on his way to the octagon, slapping hands with the fans as he comes down the aisle.

Jackson gets a mixed response in his introduction. He doesn't look happy about it, but Liddell represents the home team for UFC fans. Liddell gets another ear-splitting response in his intro.

Big John McCarthy is your referee.

Round 1: Rampage comes out and immediately establishes octagon control. Chuck throws a quick low kick. Jackson still at center octagon. Both fighters still circling, Rampage maintains octagon control. Rampage gestures with his hands, looking for action.

The two trade their first combo. And Rampage just floors Chuck with a devastating right to the jaw, Jackson jumps in with four big right hands with an elbow mixed in, and that's it. Quinton "Rampage" Jackson is the new UFC light heavyweight champion. Chuck looks like he can't believe the fight is stopped at 1:53.

That absolutely was the correct call by Big John McCarthy in stopping the fight. Liddell was rocked by the first big right hand, and was not defending several huge, powerful right hands.

Quinton "Rampage" Jackson is the new UFC light heavyweight champion. Full post to follow.

I'm going into play-by-play mode for the two main billed fights. Next up is the best pure judoka in the UFC, Karo "The Heat" Parisyan, going up against Josh Burkman.

Parisyan, an Armenian from North Hollywood who teaches judo at Randy Couture's Legends Gym, is long established as one of the most exciting fighters in the UFC, already a veteran in his mid-20s with a 24-4 record. He's beaten Nick Diaz, Matt Serra, and Chris Lytle, and has lost to Georges St. Pierre and Diego Sanchez. Burkman, a solid wrestler from Salt Lake City, is 10-3 and looking to rebound to a loss to tough Jon Fitch.

Burkman gets a healthy round of applause from the crowd, as does Parisyan. Herb Dean is your referee. The combatants have an intense eye-to-eye staredown during Dean's instructions.

Round 1: They both come out trading haymakers. Parisyan goes for a takedown, doesn't get it, gets up and hits a right. Burkman goes down, with Parisyan clutching at Burkman's left foot, but he gets right back up. Burkman just misses a big high kick and Parisyan pops him with a sharp counterpunch. Burkman with a low kick. Burkman walked into a big punch. Lots of darting and weaving. Parisyan mixing up low leg kicks  with combos. Parisyan goes for a kick, but Burkman grabs a leg and scores a takedown. Parisyan gets back up, hits him with a couple of punches, and scores one of his sensational judo throws, which gets a rise out of the crowd. They get back up, 1:20 left. Burkman goes for a takedown, Parisyan sprawls backwards, but Burkman won't let go of Karo's left leg as they work along the fence. Parisyan avoids a slam in the final seconds. Big round of applause for five minutes of solid action, round one to Parisyan.

Some in the crowd tried to start a "USA" chant. Burkman is from Salt Lake City, Karo lives in N. Hollywood, Herbie lives in SoCal. OK then.

Round 2: Parisyan with a quick jab, then a right to the stomach. Burkman tried to get in close, but Karo pushes him off. Burkman misses a wild uppercut. Burkman with some real haymakers, but then he has to block a high kick from Parisyan. Burkman connects with a right that registers, but Karo flashes "bring it" with his hands. Both fighters trading big shots. Just over two minutes left, Karo hits a knee to the head, but they continue to circle around the octagon. Anyone's round at this point. Karo pops Burkman with a low kick and a high kick, but Burkman is able to defend with Karo tries to shoot in. Some Greco grappling, with neither getting an advantage. Karo has really popped Burkman several times but Burkman is real tough and keeps on motoring. Round 2 also goes to Parisyan, as he was more aggressive and controlled the tempo. Burkman is hanging with him, but needs to take more chances.

Round 3: They stand and trade in the first minute, then Burkman shoots in on Karo and pushes him back into the fence. Karo goes for a throw, Burkman switches position, Karo tries to sink in a guillotine, and Burkman picks him up for a slam. Karo gets up and scores a trip on Burkman. They get up and clinch along the fence. Karo gets in underhooks, but lets go and they come back out to the middle with two minutes left. 1:30 left, both fighters looking to pick their spots. Burkman's either tired or thinks he has the match won, because he isn't really taking it to Karo. Burkman chases Karo backwards to finish and the two fighters embrace at the end of the match. Close third round, but I again have it going to Parisyan.

Parisyan wins on a unanimous decision, taking scores of 30-27, 30-27, and 29-28. He says he wants a title shot in his post-fight interview. It's hard to argue with him. Parisyan was supposed to fight Matt Hughes for the belt at UFC 56, but suffered a quad injury and had to pull out. There's a logjam ahead of him in the deep welterweight division, with Serra holding the belt, Hughes looking for his rematch, and St. Pierre in the picture, but Parisyan deserves his shot.

This is the final fight before the main event. They will air one of the preliminary matches, then the main event will hit the ring at midnight Eastern/9 Pacific.

Chicago's Terry Martin continues to tear through veterans in the middleweight division. Martin followed up his one-punch knockout of Jorge Rivera at UFC 68 by TKOing Seattle's Ivan Salaverry at 2:04 of the first round.

After about a minute of the fighters feeling each other out, Martin rocked Salaverry with a big right and they clinched along the fence. Martin picked Salaverry up for a slam, but Salaverry resisted the first attempt. Martin continued to hold Salaverry from behind. On the second attempt, he picked up Salaverry and dropped him so that Salaverry was on his hands and knees. Martin delivered four lefts to the back of the head before referee Mario Yamasaki stopped it.

Some in the crowd booed, thinking it was an early stoppage, but Salaverry had just been slammed to the mat and did not appear to be doing anything to defend the wide-open punches.

In his postfight interview, Martin, who came out to the ring to the sounds of Billie Jean by Michael Jackson (reason: he said Salaverry was a dancer), says he's ready to stand with middleweight champ Anderson Silva.