Experts' predictions for UFC 137

B.J. Penn (above) has won just one of his four fights since 2009, but the former two-division UFC champ is a slight favorite over Nick Diaz at UFC 137. (AP)

SI.com analysts Ben Fowlkes, Steven Marrocco, Jeff Wagenheim and Jon Wertheim provide their predictions for UFC 137 on Saturday in Las Vegas.

B.J. Penn vs. Nick Diaz

FOWLKES: A lot of people see holes in Diaz's game before they have to get in there and mix it up with him. I doubt Penn can finish him, and Diaz only gets better as the fight goes on. Penn ... not so much. Diaz by decision.

MARROCCO: Diaz is still vulnerable to takedowns, and Penn's a bit tighter on the feet. "The Prodigy" has more ways to win, and just maybe, he's a bit more clear-headed. Penn by decision.

WAGENHEIM: Penn is 1-2-1 since 2009, while Diaz is on a 10-fight win streak. But Nick hasn’t been picking on guys his own size -- in terms of talent. Penn by decision.

WERTHEIM: Diaz is like the poor man’s Penn. A potentially good fight, Penn’s X factor will be the difference. Penn by decision.

Cheick Kongo vs. Matt Mitrione

FOWLKES: Kongo sure looks impressive, but he's nowhere near the athlete that Mitrione is. I think Mitrione will show his continued improvement here, stopping Kongo late. Mitrione by TKO.

MARROCCO: Kongo is a slow starter and Mitrione has an NFL rush. But Mitrione is just crazy enough to walk into a straight right from the far more experienced Kongo, and that's bad news. Kongo by TKO.

WAGENHEIM: You wouldn’t expect a guy nicknamed “Meathead” to be a smart fighter, but Mitrione is capable of making Kongo’s head spin by using his cranium to control the way the fight is fought. Mitrione by TKO.

WERTHEIM: Mitrione is undefeated and a potential star in the making. Kongo has the experience (and kickboxing), Mitrione has momentum. Mitrione by decision.

Mirko Filipovic vs. Roy Nelson

FOWLKES: The nostalgic part of me would love to see Cro Cop get one last headkick kayo, but the realist in me knows it's probably not going to happen. A better bet is Nelson landing that looping right. Nelson by KO.

MARROCCO: Filipovic browbeat the UFC into giving him one last fight, and it's three too many. His speed isn't there, the high kick is gone, and he's prone to lapses in consciousness. Nelson by decision.

WAGENHEIM: “Big Country” was on the rise in the heavyweight division until he ran up against top-level guys. Good thing he’s not facing the old “Cro Cop,” but rather an old Cro Cop. Nelson by TKO.

WERTHEIM: Cro Cop is a borderline legend but should probably be retired by now. With any luck, Nelson wins swiftly and Cro Cop walks away while he still can. Nelson by TKO.

Scott Jorgensen vs. Jeff Curran

FOWLKES: Jorgensen is better in almost every area. Curran is scrappy and experienced, but at this level that's just not enough. Jorgensen by decision.

MARROCCO: Curran is a great ambassador to the sport, but I fear he has far too many miles on his body to match Jorgensen's aggression. Jorgensen by decision.

WAGENHEIM: Jorgensen is not the guy you want to see across the cage when you step in for your first top-level fight in a couple of years. Jorgensen by decision.

WERTHEIM: Interesting contrast of styles and experience levels. We’ll go with experience here. Curran by decision.  

Hatsu Hioki vs. George Roop

FOWLKES: Roop is big for the weight class, but Hioki is the sharper all-around fighter. As long as he doesn't allow himself to get bullied, I think he takes this. Hioki by decision.

MARROCCO: Hioki is dynamite when he's on point, and if octagon jitters don't spoil the party, this is his fight to lose. Hioki by TKO.

WAGENHEIM: Only a single split-decision loss stands in the way of Hioki being on a 14-fight unbeaten streak. But he’s 0-0 in the UFC, so he has something to prove. Hioki by submission.

WERTHEIM:

Hioki by submission.