Here's a copy and paste of one of my older posts regarding this match up:
I think this match up is very intriguing because of the skills both fighters bring.
BJ Penn has powerful hands and isn't afraid to take a punch. Sherk hands are quick and accurate, look at the Diaz fight, he schooled the taller, longer fighter. Edge is BJ, he has the power and is fairly accurate as well. He aims for your face and hits hard.
BJ's wrestling is underrated in my opinion. He has trained with some of the best. The only wrestler to really outwrestle him recently is GSP and that was only after he gassed. Sherk on the other hand is strong and good at control, I have no doubt that he will get takedowns but... No edge here, Sherk is strong but BJ is adept at defending using his length and flexibility. Sherk will get some takedowns But I think they wil be few and far between with BJ sweeping or escaping every chance he gets.
On the ground:
BJ is second to none on the ground his sweeps and transitions come from nowhere. His ground and pound is powerful and aggressive. Sherk's passing of the guard is good and he uses his strength well on the ground. The thing about last weekend's fight (Franca fight) I noticed was him not doing much damage to Hermes over the course of the fight, despite being on top for most of it. If he has a hard time with Hermes what will he do with Penn who is bigger than Hermes and better at the ground game. Edge is Penn here.
This is where Sherk shines like no other. He is a monster. He keeps the pressure on for 25 minutes and doesn't wear down. His strength is another factor that helps him control and neutralize his opponents. His only losses are to the 2 strongest WWs in the UFC. BJ has learned his lesson, and just like with his wrestling, he's sought help from professionals that will bring him to his peak. Will it be enough to wage a 5 round war with a monster?? I certainly hope so. Edge is definitely Sherk.
BJ is a great mixed martial artist has improved in every aspect of his game. His melding of styles (IMO) is second only to Fedor. Sherk is a like a wrestling match with a jack hammer. He is just going to grind you into dust with every passing moment is lost energy to which he has an endless supply, which makes him only stronger as the match continues.
I know it seems like I think BJ is going to dominate. But, that's far from the truth. Sherk has just as much of a chance to win as BJ. The only reasons I have to put BJ ahead are their matches with like opponents. And BJ's match up with Hughes in particular because I regard Hughes and Sherk pretty equal in the grappling areas. Oh and because I'm quite biased as a BJ fan.
EDIT: I'm sorry this is long.
"You must first believe if you are to achieve. That rhymed... unintentionally."
Favorite MMA Fighters:
BJ "The Prodigy" Penn
Randy "The Natural" Couture