The linebacker pipeline is flowing quite freely between USC and the NFL.

With four linebackers drafted last year and eight selected in the last three seasons, the Trojans are becoming an NFL linebacker factory and making a strong case to be Linebacker U.

"We love seeing our guys take it to the next level," Coach Pete Carroll said. "It's a testament to our program when guys can excel in the NFL like our linebackers have been doing recently."

The 2009 NFL draft saw Brian Cushing, Clay Matthews, Rey Maualuga and Kaluka Maiava get picked, with the four Trojan rookies already holding starting spots during all or part of the season. Cushing has won two AFC defensive player of the week honors and leads all rookies with 78 tackles, while Maualuga, Matthews and Maiava are all the in top eight tacklers among rookies this season.

And then add to that quartet Lofa Tatupu and Keith Rivers, two other recent USC alumni who now star and start in the NFL. Tatupu has been a three-time Pro Bowler and has started 68 games in his four-plus seasons in the NFL, and Rivers has started 15 games in less than two full seasons.

So why the smooth transition and early success for Trojan linebackers in the NFL?

"We have a pro-style defense here," sixth-year linebackers coach Ken Norton Jr. said. "It's a proven scheme that has been tested over the years."

That's not the only reason USC linebackers are growing and developing into standout pros. It also helps that Norton had a 13-year career in the NFL and won three Super Bowls, and Carroll spent 16 years as a defensive or head coach in the League.

"I played it, Coach Carroll coached it," Norton said. "We understand the type of people that make this work."

And even before the recent flux of Trojan linebackers in the NFL, greats such as Junior Seau, Willie McGinnest and Chris Claiborne starred, combining for 43 seasons, 14 Pro Bowls and six Super Bowl appearances (and Seau is still active).

"It's a remarkable tradition of USC linebackers in the NFL, and it's something we hope continues well into the future," Carroll said.