Starting Wednesday, 329 candidates for the 2010 NFL draft will arrive in Indianapolis for the 32-team scouting combine, but underclassmen will receive the main attention. Thanks to a deep group of underclassmen, the 2010 draft class is considered to be one of the richest in years.
As many as 20 underclassmen could be selected in the first round, and more than a dozen others could fill the second round. Because more athletes are expected to work out and run at the combine than in past years, the results from Friday through next Tuesday could determine where players will go in this year's draft.
Here are the five main storylines for the combine:
1. Colt McCoy's place in the draft: Because they are recovering from injuries, Sam Bradford of Oklahoma and Jimmy Clausen of Notre Dame won't work out at the combine, but they will be present for important physicals. That clears the way for McCoy of Texas to gain ground on them by throwing the football. The knock on McCoy is his arm strength; despite his accuracy, he is considered a second- or third-rounder because he doesn't wow scouts with his throwing. Wisely, McCoy said he will throw and work out. A good workout could open eyes for first-round consideration.
There is some debate that Dan LeFevour of Central Michigan might have moved ahead of McCoy on some teams' boards after the good work he did during the Senior Bowl. A year ago, Mark Sanchez solidified his first-round status by throwing at the combine, even though he wasn't perfect. Tony Pike of Cincinnati and Tim Tebow of Florida also will be interesting to follow. Pike didn't hurt himself at the Senior Bowl, while Tebow hurt his stock because he showed a flawed throwing delivery. Tebow is working on refining his game and will not throw until the Gators' pro day on March 17.
Overall, it's an interesting class of quarterbacks. As many as nine could go in the first four rounds. Jevan Snead of Mississippi could use a good throwing performance to change perceptions that he made a mistake by turning pro too early. Accuracy was a problem in his final season in college.
2. Competition between DTs Ndamukong Suh and Gerald McCoy at the top of the draft: Suh is putting pressure on every player considered near the top of the draft. Although the Nebraska star has been considered the top pick for more than a month, he says he will work out and try to put on a show at the combine. That could pressure McCoy and Tennessee safety Eric Berry to work out as well.
Suh is a freak. Some consider him to be the best defensive tackle prospect since Warren Sapp. The St. Louis Rams could take Suh with the first pick, and there is some thought that the Tampa Bay Buccaneers would consider trading up from No. 3 to grab him.
Drafting defensive tackles among the top five picks usually leads to disappointment; the last great one drafted that early was Cortez Kennedy (Seahawks) in 1990. But defensive tackle is considered the best position in this draft. As many as 13 defensive tackles could come off the board in the first four rounds, and at least five could go in the first round. Dan Williams of Tennessee, Jared Odrick of Penn State and Brian Price of UCLA all could be pressed to work out to secure first-round spots.
Another interesting sight will be the weigh-in for Terrence Cody of Alabama. Cody disappointed scouts at the Senior Bowl by weighing in at 370 pounds, but he solidified his second-round status by having good workouts.
3. Mays' 40 time: Mays' 40-yard dash time could be a huge story. It's hard to believe he has something to prove, but he does. A year ago, many considered Mays a top-five pick, but he elected to stay at USC for his senior season. Now, he's considered the second-best free safety in the draft behind Berry. If Mays runs a sub-4.4 40, he could jump back into the top 10 overall, but he's currently expected to be drafted in the middle of the first round. Physically, Mays is a freak. He's 6-foot-3, 231 pounds, and a sub-4.4 40 could be huge in improving his stock. Berry is considered a top-three pick because of his playmaking ability and is expected to establish himself immediately among the top safeties in the NFL.
A great safety with mobility and playmaking ability is vital in this day and age, as teams routinely face quarterbacks throwing from three- and four-receiver sets. Too often, defenses with average coverage at the safety position get carved up by good quarterbacks. Mays needs a fluid workout and a great 40 time to come closer to the perceptions scouts had of him in 2009.
4. The RB hierarchy: Who will establish themselves as the No. 2 and No. 3 running backs? Just about everyone agrees C.J. Spiller of Clemson will be the first runner taken, probably in the top 15. Who will follow Spiller could start to become clearer at the combine. The runners to watch are Ryan Mathews of Fresno State, Jahvid Best of California, Anthony Dixon of Mississippi State, Toby Gerhart of Stanford and Jonathan Dwyer of Georgia Tech.
I'm personally interested in watching the progress of LeGarrette Blount of Oregon. Blount was a 245-pound beast at the Senior Bowl who was hard to tackle and showed good power. The Seahawks will be among a handful of teams seriously looking at running backs, but their main goal will be trying to find a gem in Rounds 2 through 4. Spiller could be an option for them if he's available at No. 14.
5. Dez Bryant: Bryant, who didn't play for Oklahoma State last season because of NCAA rules infractions, is considered one of the best receiving prospects this year. But is he Calvin Johnson or Roy Williams, the struggling Dallas Cowboys receiver? Bryant has the raw ability to match up with top NFL receivers such as Larry Fitzgerald, Johnson and Andre Johnson of the Texans. He's 6-2, 220 pounds, and he has great hands.
At an ESPN skills challenge in Miami during Super Bowl week, though, Mardy Gilyard of Cincinnati and Jordan Shipley of Texas outperformed Bryant. He needs to win over teams during interviews, and it would help if he could put on a show in workouts. The team that might be studying Bryant most is the Denver Broncos, who could look to have him replace Brandon Marshall if Marshall can generate the right trade value.
John Clayton, a recipient of the Pro Football Hall of Fame's McCann Award for distinguished reporting, is a senior writer for ESPN.com.