Success can be costly for the nation's best college football teams.

When Michigan won a national championship in 1997, the Wolverines lost Heisman Trophy winner Charles Woodson. He skipped his senior season to enter the NFL.

The last two times Nebraska won national titles, the Cornhuskers lost tailbacks Lawrence Phillips in 1996 and Ahman Green in 1998. Both elected to leave early.

Miami also lost a tailback after winning its last national championship in 2001 when Clinton Portis left early. Texas lost its quarterback after winning the 2005 crown when Vince Young decided to bolt.

Now it's Florida's turn. The Gators didn't merely lose a player – they essentially lost their defense from the 2006 championship team.

Four starters on Florida's sixth-ranked defense – players who helped suffocate Heisman Trophy winner Troy Smith and high-scoring Ohio State in the national title game – left their final seasons of eligibility on the table to enter the NFL in 2007.

That's the most underclassmen to leave a national championship team since the NFL opened the door to juniors in 1990. Factor in the five graduating seniors and the Gators will be turning over virtually their entire defense in 2007.

Gone are team MVP Reggie Nelson, a safety. Linebacker Brandon Siler, who won the Orange Helmet Award as the team's best player, also decided to leave. So did defensive end Jarvis Moss, who led the team with four forced fumbles and finished with a runner-up 7½ sacks. Cornerback Ryan Smith, who led the Southeastern Conference with eight interceptions, also left.

It wasn't a group decision by those four juniors. But it was a group discussion.

"We talked about it every now and then," Siler said. "Even a couple of the guys who stayed in school talked about it. I was probably the closest one to going back."

But in the end, Siler decided there was nothing left to accomplish at Florida after spending three years on campus.

"I had started for 2½ years, whereas most people redshirt or sit out a year," Siler said. "We won an SEC championship and a national title, two things that I aimed to do at Florida. So I accomplished my goals and thought I'd be drafted pretty high."

Moss spent four years at Florida, having worn a medical redshirt in 2004. He also cited the national championship as a reason for his early exit.

"I had a terrific season," said Moss, a product of Denton Ryan. "We accomplished a lot as a team, winning the SEC and then going out and dominating in the national championship game. I consulted with my coaches, my family and the people who are close to me and we made a decision."

Nelson spent four years on two college campuses – two at Coffeyville Junior College in Kansas and two at Florida. But he didn't play football in his first year at Coffeyville, so he was entitled to another year of eligibility at Florida. But he figures to be the highest Gator on the 2007 draft board, a potential top-20 pick. So it's on to the NFL.

Troy Smith also spent three years on two campuses – three at Utah and one at Florida. He graduated from Utah in three years, which allowed him to transfer to another NCAA Division I school without having to sit out a year. So he followed his former Utah coach, Urban Meyer, to Florida.

Like Siler, he saw no point in sticking around in 2007.

"I had a college degree, we won a national championship and I had a great year," Troy Smith said.

Don't shed any tears for Florida, though. Southern Cal lost five underclassmen to the NFL last April and still went on to finish 11-2 in 2006. The great programs just reload.

"There's still a lot of talent at Florida," Siler said.

See more at www.wfaa.com