PROVO — They're big, tough and would love nothing more than to let it show this year behind BYU's veteran offensive line.

They're a throwback to the likes of Lakei and Hema Heimuli, Reno Mahe, Casey Tiamalu and Peter Tuipolutu. While none are sprinters, they all are capable of making huge plays. And they are competitive to the core. Meet the Cougar backfield, led by 240-pound Fui Vakapuna, 235-pound Manase Tonga, 221-pound Harvey Unga, 222-pound Wayne Latu and Joe Semanoff. Pound for pound, they may be the most athletic players on BYU's team outside of the corps of linebackers.

Most could play linebacker.

"We believe we will be able to move the ball this season," said Tonga. "Behind this great offensive line, we will make a lot of plays, and do it against anybody, not just in league play."

Vakapuna, who turned a lot of heads a year ago, agreed. "You saw it in the first scrimmage. We are an offense that can spread it out on a defense, and we can bring everybody down and run it. We're playing it safe right now, but when the hitting starts, it will be a different story.

Vakapuna has averaged about 5 yards per carry in two seasons at BYU, years separated by an LDS mission. He played about half of BYU's games last year before a foot injury sidelined the former East High all-stater.

Tonga has averaged 4.6 yards a carry in two seasons playing in the shadow of all-time rushing leader Curtis Brown.

Vakapuna, Tonga, Unga and Latu are sons of men who grew up playing rugby on the south Pacific Island of Tonga. They like the idea of physical play and their role in it. "It's just smash mouth football, "said Vakapuna. "I think that is what the coaches are thinking about."

The newest face in the bunch is Unga, an all-state runner at Timpview High two years ago, who enters his freshman season after redshirting a year ago due to a hip ailment. He waited a year before enrolling at BYU after leading the Thunderbirds to a 4A title in 2004.

He committed to Utah, then switched to BYU when running back coach Lance Reynolds decided to stay after missing out on the head coaching job vacated by Gary Crowton after the 2004 season.

In BYU's first scrimmage, people saw what Cougar coaches and teammates already learned about Unga: he's big, fast, can catch and make plays such as the 63-yard catch and run he ripped off.

Unga has sat and watched his counterparts the past two seasons.

"I respect those guys. They've been through all the things I haven't been through." He considers himself a combination speed and power running back. He is the most flexible back in the Cougar arsenal now that freshman J.J. Diluigi will likely redshirt following foot surgery.