Chris Leben returned to the UFC following a year-long drugs suspension stemming from his UFC 138 loss to Mark Munoz. Unfortunately, he opened UFC 155's main card against short-notice replacement Derek Brunson, and the two combined for a horrible fight which Brunson took via unanimous decision. It marked the 3rd loss in 4 fights for The Crippler, who looked every bit a shot fighter as you could expect from someone who has been in so many wars. Dana White expressed his regret over putting Leben in particular on the main card. From his interview with MMA Junkie:
"I love Chris Leben, personally and professionally," White said at the show's post-event news conference. "But tonight, I think I made a mistake putting him on the pay-per-view. I should have had him on the undercard. He's been off with personal problems for a while. He's had a lot of time off, and he looked slow tonight. I wasn't crazy about that fight. That wasn't my favorite fight of the night, that's for damn sure."
The FX prelims had two fights (Brad Pickett vs. Eddie Wineland and Melvin Guillard vs. Jamie Varner) that could've easily been swapped from FX to PPV, but they chose to keep Leben on the main card even after his original opponent of Karlos Vemola pulled out with an injury. From what I recall Leben was only elevated to main card status following the endless supply of injuries that ravaged the original lineup.
Brunson wasn't let off the hook, either.
"The other kid was looking at the clock like he was a 14-year-old waiting for school to get out the entire fight – looking at the clock," White said. "You're in the UFC your first time, and I wasn't very impressed."
To be fair to Brunson he was fighting on short-notice and obviously didn't have a full camp. That said, if you watch his fights in Strikeforce (particularly that awful fight against Nate James), the odds of entertainment in this one were dependent on someone getting immediately knocked out. Otherwise Brunson isn't exactly the most exciting fighter in the world.
Leben definitely deserves some prelim time, preferably against other strikers like Jared Hamman, while Brunson is probably going to get the Nik Lentz treatment and get shunted to Facebook and stay there until further notice.