**There will be 323 prospects at the annual NFL scouting combine, with the first group arriving on Tuesday. Players are split into groups spread over four days. The first is comprised of specialists, offensive linemen, and tight ends; the second group includes quarterbacks, wide receivers, and running backs; the third group has defensive linemen and linebackers; and the final group consists of defensive backs.

They all arrive sequentially during the next four days, and cycle through the following schedule: registration, pre-exam, X-Rays, orientation, and team interviews on the first day; measurements, medical examinations, media interviews, and team interviews on the second day; NFLPA Meeting, psych testing, bench press, and team interviews on the third day; an on-field workouts on the fourth day.

The on-field testing, which is the televised portion of the event, goes from Friday to Monday. So if you want to watch the defensive backs run the 40-yard dash, that will happen on Monday.

The combine has taken on a life of its own, and some drills or tests do not an indicate how a player functions at his position. Plus, players have trained for a combine. The days when Mike Mamula can come out of nowhere with a combine workout are gone, so players are more prepared for the testing. But it allows for standardized scores, which is important when teams are sorting through such a large number of prospects. Here is what NFL Network analyst Mike Mayock said about the drills/testing:

"Everybody has got an opportunity to train for it, and you're in the best shape of your life, so let's benchmark everybody on the field on the same day at the same time.

"So conceptually it makes sense, but sometimes it gets kind of skewed, and obviously the 40 is a big deal. That seems to be the marquee event. I don't really care as much about a 40-yard dash for an offensive lineman. I look at their 10-yard dashes, although it's hard to say that Dontari Poe at 346 pounds running 4.98 is not impressive.

 "I don't think the 40 is that important for offensive linemen and defensive linemen. I think it is very important for skill position people.

 "I think the change-of-direction stuff, the short shuttle and the three-cone is important for the linebackers, the defensive backs, the running backs. You get to see quickness, change of direction. You see whether a guy is quicker than he is fast in a straight line, and those are important things.

 "The broad jump and the vertical jump are really lower body explosion, and it's another cross-check. If a guy is a 4.5 40 guy, he probably should be jumping 35 inches in the vert. If he only jumps 30, there's a question why. It all kind of balances out. There's checks and balances everywhere, but I'd throw out some of the stuff, and it's really position oriented, and I think the important thing is after those drills are over and the coaches come out and put them through football drills, I think we really get an opportunity to see one kid after another in their movement skills, and it kind of exposes flaws.

"If you're a defensive back and you can't open your hips, things like the coaches can see immediately, and you've got 30 defensive backs in a row going in one drill, you can see which ones are natural and which ones aren't, and then you've got to go back -- if you put too much on that, obviously, it can't overwhelm the grade you give them on tape, but it's just another cross-check."

**The quarterbacks are usually the most popular players at the combine, and the top two quarterbacks this season are Florida State's Jameis Winston and Oregon's Marcus Mariota. The Tampa Bay Buccaneers, who have the No. 1 pick, are expected to select a quarterback. It's not believed to be a deep quarterback class after the top two passers. UCLA's Brett Hundley and Baylor's Bryce Petty will also get attention.

The draft class is deep at running back and wide receiver, according Mayock. He believes it's "very thin" at quarterback and safety.

"I think the rest of the positions are solid," Mayock said. "So overall, a good class."

Beyond Winston and Mariota, the headliners this season include USC defensive lineman Leonard Williams, Nebraska pass rusher Randy Gregory, and Alabama wide receiver Amari Cooper.

The top local player is Arizona State wide receiver Jaelen Strong, a West Catholic product and Philadelphia native. Penn State and Rutgers both have prospects at the combine, but they are not among the top at their position. Penn State Tight end Jesse James could move up at his position.

**Aside from the draft prospects, the combine also serves almost as an offseason convention for the NFL. Coaches, executives, scouts, and agents are all in close proximity, so there is always interest and discussion about potential free agents and teams with major offseason moves upcoming.

Most teams have their head coach and/or general manager address reporters on the early days of the combine. This is the first season in recent years that the Eagles are not expected to have anyone meet with the media. Head coach Chip Kelly has not spoken to reporters until the end of the season, and the team has not introduced new vice president of player personnel Ed Marynowitz to the public.

The Eagles' pressing offseason questions include what to do with free agent wide receiver Jeremy Maclin and linebacker Brandon Graham; which defensive backs they can sign in free agency; and whether they will stay at No. 20 or try to move up in the draft for Mariota.

zberman@phillynews.com
@ZBerm