Though many top college players decline to participate in drills and tests -- choosing instead to perform later in individual workouts at their respective schools -- the NFL still values the scouting combine, held annually in Indianapolis. It's a venue for teams to thoroughly examine each prospect physically and psychologically, something scouts can't do in the fall.

Here's a position-by-position look at players whose stock rose or fell at this year's combine.

Quarterbacks: Fresno State's David Carr was erratic in some of the drills, but he continued to show great arm strength. The Texans, who are expected to take Carr with the No. 1 overall pick, saw what they needed to see.

Oregon's Joey Harrington was impressive in passing drills. More important, he passed his physical, proving that the knee injury he suffered in the East-West Shrine Game was minor.

Tulane's Patrick Ramsey pulled ahead of Illinois' Kurt Kittner as the No. 3 quarterback in the class. Ramsey was in excellent shape and showed tremendous accuracy while Kittner failed to show adequate zip on deep out routes.

Sam Houston State's Josh McCown continued his magical postseason ride, running a 4.57 40, recording a 38-inch vertical jump and showing an adequately strong arm. LSU's Rohan Davey bypassed the drills but was 12 pounds lighter than he was at the Senior Bowl -- a victory in itself.

Running backs: Michigan State's T.J. Duckett and Ohio State's Jonathan Wells, who weighed in at 241, are said to be in top physical shape but did not work out. Miami's Clinton Portis weighed in at less than 200 pounds, which could hurt him. Many teams aren't enamored with drafting a back in the first round who could amount to a third-down specialist.

Boston College's William Green was a bit disappointing with a 4.57 40, but he had put on some weight, bench-pressed 225 pounds an impressive 27 times and came across well in interviews.

The player who might have improved his status the most was Stanford's Brian Allen, who ran a 4.45 40 and did 19 reps in the bench press. Georgia Tech's Joe Burns hurt his status the most by running a 4.77 40.

Wide receivers: This group resembled an Olympic track team in both a good and bad sense. Virginia Tech's Andre Davis, Florida State's Javon Walker, Utah's Cliff Russell, Auburn's Tim Carter and Kansas State's Aaron Lockett all ran under 4.4 in the 40. However, many of the top receivers, including Florida's Jabar Gaffney, didn't catch the ball consistently.

Georgia Tech's Kelly Campbell ran one of the quickest 20-yard times but tweaked his hamstring and pulled up early in the 40. Hawaii's Ashley Lelie, who had promised to run under 4.3, did not participate after suffering a hamstring injury before the combine.

The player who helped himself the most out of all the positions was Richmond wideout Ryan Tolhurst, who might have become a late-round pick with an excellent all-around workout. The biggest disappointment had to be Pitt's Antonio Bryant, who ran a 4.58 and a 4.64 in the 40.

Tight ends: Wisconsin's Mark Anelli, Missouri's Dwayne Blakely and Virginia's Chris Luzar are three late-round prospects who stood out.

Oklahoma's Josh Norman, who weighed 232 and ran the 40 in the mid-4.5s, is an undersized but athletic tight end much in the mold of Green Bay's David Martin.

Miami's Jeremy Shockey and Colorado's Daniel Graham, the top two prospects, did not participate in the drills.

Offensive line: Miami's Bryant McKinnie did not work out but helped solidify the top tackle spot by passing his physical and weighing 343 pounds.

Texas' Mike Williams, McKinnie's competition for the No. 1 tackle in the draft, has a partly torn ACL that might need surgery. Williams weighed 378, 15 pounds over his playing weight, but scouts thought he looked in great condition. In fact, they thought the extra weight could have propelled him past McKinnie had the knee injury not been discovered.

Ohio State's LeCharles Bentley secured the top spot among centers by running a 5.16 40 and weighing 299. Texas A&M's Seth McKinney silenced some critics by running a 4.97 40. Both should be drafted on the first day.

Colorado tackle Victor Rodgers hurt himself by posting an embarrassing 40 time of 5.76.

Defensive line: More prospects from this group raised their stock than at any other position. LSU end Jarvis Green's speed and athleticism were in question until he ran a 4.79 40 and recorded a 9-1 in the broad jump and a 31-0 in the vertical leap.

Arkansas end Carlos Hall almost made as big a splash by running the 40 in 4.65 and 4.66 and posting 11-0 in the long jump and 40-0 in the vertical leap. Virginia Tech end Derrius Monroe may have moved from the late rounds to the middle rounds after weighing 273 and running a 4.53 40.

Alabama-Birmingham end Bryan Thomas (266 pounds) put together a stunning performance, running a 4.48 40 and bench-pressing 225 pounds 33 times. His workout could earn him a first-day selection.

Tackles Nate Dwyer of Kansas and Anthony Weaver of Notre Dame also raised their stock with good combine performances, but Ryan Sims of North Carolina might have leveled off after a strong Senior Bowl. Kentucky end Dennis Johnson and Fresno State tackle Alan Harper both probably hurt their draft status.

Linebackers: Northwestern's Napoleon Harris solidified his spot as the top overall linebacker by weighing 253 pounds, running a 4.54 40 and producing 27 reps in the 225-pound bench press.

Speed was prevalent here. Undersized players such as UCLA's Robert Thomas, Washington State's Raonall Smith and Oregon State's James Allen all ran in the 4.5s. Oklahoma's Rocky Calmus may have solidified a first-day selection by running well after adding 14 pounds.

Purdue's Akin Ayodele, a 'tweener linebacker/end, helped his cause by bulking up and doing 26 reps in the bench press. Hampton's Greg Scott entered the weekend striving to prove he could be a rush end but was set back by his failure to add strength and bulk. As a result, scouts asked him to participate in the linebacker drills.

Secondary: Texas' Quentin Jammer and Miami's Phillip Buchanon are the top two candidates, but there is heavy competition for the No. 3 spot. Nebraska's Keyuo Craver, Miami's Mike Rumph, Florida's Lito Sheppard and Ohio State's Derrick Ross are possibilities. Craver had the edge in early January, but a stinger in the Senior Bowl and a 4.59 40 at the combine didn't help him.

Tuskegee's Roosevelt Williams made up for a disappointing week at the Senior Bowl with 22 reps in the bench press.

There were some concerns at safety, which had been tabbed as the strongest position in this year's draft. Oklahoma's Roy Williams, the top prospect, showed up overweight at 230 pounds. Pitt's Ramon Walker, an early entry, pulled out of drills with a pulled muscle. And Colorado's Michael Lewis ran a 4.72 in the 40, causing further concerns about his ability to cover downfield.

---

Tell us what you think on the new 49ers Clubhouse message board.