NAPA -- Mike Brisiel shrugged and in his best "aw, shucks" voice downplayed the notion that he played on a broken leg.

"It was the fibula," Brisiel said. "It wasn't the main weight-bearing bone."

The fifth-year veteran guard was the closest thing the Raiders had to a big-ticket item in the NFL free-agent market. Brisiel was signed in March to a four-year contact worth a maximum of $20 million, including a reported $8 million signing bonus.

Brisiel has never been to a Pro Bowl in five seasons with the Houston Texans. He wasn't even drafted coming out of Colorado State. And his only honor as an NFL player is being named to something called the USA Today "All-Joe" team in 2008. Brisiel, like defensive end Dave Tollefson, was signed in part because of his mindset.

During training-camp blocking drills, it isn't unusual to see Brisiel get the worst of it, as happened the other day against defensive tackle Tommy Kelly.

Coach Dennis Allen had a quick answer when asked what made Brisiel such an important addition.

"Tough. He's got that mental toughness we're looking for," Allen said. "The more guys you can get that fit that quality, it permeates the locker room."

Brisiel injured his right leg Oct. 9 against the Raiders and played with what he called a "hot spot" for several weeks. When the leg finally gave way Dec. 11, it was repaired with six screws and a plate.

"The doctor described it like a paper clip," Brisiel

said. "You keep bending a paper clip, it changes colors and gets weaker, but it's not like it's broken or anything. And then in the Cincinnati game, it finally broke all the way through. It was one of those things. I knew it was going to break sooner or later. I was just trying to keep going as long as possible."

After 26 days of rehabilitation, Brisiel played in a 31-10 playoff victory over the Bengals.

Told of Allen's assessment, Brisiel said, "I don't know if it's so much toughness. I don't like to get beat, and I don't like to embarrass myself out there. And I'm not the most athletic guy, so I try to find any way possible to get the job done. That's my mentality."

Right tackle Khalif Barnes is Brisiel's roommate and a kindred spirit, having played on a broken fibula as a rookie with the Jacksonville Jaguars.

"Off the field, he's a great guy," Barnes said. "On the field, it's good for me because I know that whatever happens during the course of a game, unless he's about to die or something, he's not going to come off that field."

With the Raiders reverting to a zone-blocking scheme, Brisiel is a key addition, hence the big contract.

It all sneaked up on Brisiel, who said he never thought in terms of a big-time payday.

"It was just, 'Stick around one more year, stick around one more year,' " Brisiel said. "Nothing's changed for me. I've still got to prove myself to a new team and prove myself to new coaches."

For more on the Raiders, visit the Inside the Oakland Raiders blog at ibabuzz.com/oaklandraiders. Follow Jerry McDonald on Twitter at Twitter.com/Jerrymcd.