GREEN BAY — With the recent proliferation of 3-4 defenses in the NFL, evaluating linebackers — particularly outside linebackers — entering the draft has become an increasingly difficult proposition for teams that employ that scheme.

"Outside 'backer is an interesting position for us because almost every defensive end we watch has to be projected to outside linebacker in the 3-4," said Cleveland Browns general manager Phil Savage, whose team uses the 3-4 under coach Romeo Crennel. "We've looked long and hard at that."

Added New York Jets coach Eric Mangini, whose team also uses the 3-4: "That's always something that is something that you have to deal with. And you do look at some defensive ends and try to project how they look standing on their feet. And then (you look at) some of the outside linebacker-types (who) may have to move inside in the 3-4 system. So there is quite a bit of projecting there. You just try to do the best you can there."

The bottom line? "You have to find guys who fit your scheme," said Baltimore Ravens GM Ozzie Newsome, whose team also uses the 3-4.

Of course, when looking at the linebackers in this year's draft, one thing is certain: USC's Keith Rivers will be really good in whatever scheme he ends up in. So he could play for the roughly one-fourth of the league's teams that use the 3-4, or he could fit in just fine with a traditional 4-3 team.

"He is a real talent at that position," Savage said.

In an otherwise mediocre year for linebackers — "The linebacker depth is a little bit down, especially on the inside. It's not as deep as it has been in the past," San Francisco 49ers GM Scot McCloughan said — Rivers could be the only linebacker picked in the first round, and he could go in the top 10. At the Senior Bowl in January, he played all three linebacker spots.

Although did little at the scouting combine in Indianapolis because of a sprained ankle, he has been steadily rising up draft boards since, his already solid resume reinforced by a strong pro day workout at USC on April 2.

"I think every linebacker's goal is to be the first linebacker picked. And that's definitely mine," said Rivers, who wore the prestigious No. 55 jersey for the Trojans (previously worn by Junior Seau, Willie McGinest and Chris Claiborne, among others).

USC coach Pete Carroll referred to Rivers a "model Trojan," and unlike a number of other linebackers who come with varying character questions, Rivers looks to be a safe pick in that department. He's been blogging about his experience with the draft process, and he is still attending classes to earn his degree in public policy development — rather than dropping out of school to prep for the draft.

"If I was going to take off this spring semester I should have just left (early) last year," Rivers said. "If I'm going to come back for my senior year, it's going to be to get a degree."

After Rivers, the next linebackers are Jerod Mayo of Tennessee, Curtis Lofton of Oklahoma and Dan Connor of Penn State in the less-than-stellar group.

"It's not the strongest of all the positions in the draft," Pittsburgh Steelers director of football operations Kevin Colbert said. "But it's still pretty good."

QUICK READ: LINEBACKERS

THE TOP FIVE

Keith Rivers, Southern Cal (6-foot-2 1⁄4, 271 pounds, 4.7 seconds in the 40-yard dash): Remarkable physical specimen who played four years for Trojans, starting his final three seasons. Smart, hard-working player who will be a standout weakside linebacker in the NFL.

Jerod Mayo, Tennessee (6-1 1⁄4, 242, 4.58): Started 14 games as a junior last season, recording 140 tackles, and one interception. Powerful tackler whose past knee problems create durability concern.

Curtis Lofton, Oklahoma (6-0 1⁄8, 246, 4.83): Junior who started 14 games last year (four in the middle, 10 on the strong side) and had 157 tackles, one sack, four forced fumbles and three interceptions. Lacks ideal speed and height.

Dan Connor, Penn State (6-2 3⁄8, 231, 4.8): Latest in line of Nittany Lions linebackers. Finished his career as school's all-time leading tackler but might not have the bulk to succeed at the next level.

Bryan Kehl, BYU (6-2 1⁄4, 242, 4.69): A 13-game starter on the weak side. Helped himself considerably with strong showings at East-West Shrine Game and scouting combine.

THE PACKERS' PERSPECTIVE

This would seem to be the one position where the Packers are set. Middle linebacker Nick Barnett and third-year weakside starter A.J. Hawk return, while incumbent strong-side starter Brady Poppinga will compete with free-agent signee Brandon Chillar for the other spot. Whoever loses that battle will work as a backup and play in sub packages.

Meanwhile, special teams ace Tracy White re-signed, and middle linebackers Desmond Bishop, who made the team as a sixth-round pick last year and showed promise, and Abdul Hodge, a 2006 third-round pick who is coming off double knee surgery, also are in the mix.