INDIANAPOLIS -- With a full year of scouting and the all-star games in the rearview mirror, there still is no consensus group of top five players in this year's draft class. Of course, a lot can still change as the evaluation process winds down over the last two months.

The NFL scouting combine gets underway here on Thursday, and there will be a litany of Pro Day workouts to break down between now and the draft on April 26-27. But the lack of a "sure thing" right now has the owners of the top five selections -- Miami, St. Louis, Atlanta, Oakland, and Kansas City -- understandably on edge.

Because of a lack of a stud group of prospects that sets itself apart from the rest of the class, every one of those teams is looking to get out of the top five, but they are finding very few takers.

Most general managers and personnel people I talk to believe the depth of overall talent makes the second half of the first round a better value than one of the top five. That is due in large part to the fact that the positions that normally drive interest in the top of the draft are lacking, including quarterbacks, pass rushers, cornerstone left tackles, and shutdown corners.

So where are they?

Some fans will immediately point to Boston College's Matt Ryan or Louisville's Brian Brohm as potential franchise signal callers. But despite Ryan's heroics throughout last season, his performance was uneven, particularly at the end of the season; Brohm was sabotaged by Louisville's meltdown in 2007 and doesn't have Ryan's arm strength; and neither played in the Senior Bowl.

Most scouts have Ryan in the top 10 overall picks, but the top five might be a reach unless he really shows something spectacular in workouts at the combine.

Virginia defensive end Chris Long has been a popular choice among name-droppers as a top prospect. But privately, some scouts are beginning to wonder if he has maxed out. Does his 6-foot-3 frame have the ability to carry any more than the 275 pounds he is carrying right now? And can NFL coaches get anything more out of him?

This is a kid who has already learned all the pass-rush moves from his dad, former Raiders great Howie Long, and even as the most polished pass rusher in the draft, he hasn't been a great finisher. Coaches and scouts have to wonder if he can be a highly productive player at the next level. What you see is what you get is how one GM described him. Another GM agreed, but still thought what Long offered was good enough to take him high in the draft.

If not Long, many teams could instead opt for a late riser like Ohio State's Vernon Gholston, who has the versatility and athleticism to play with his hand down as a 4-3 defensive end or play outside linebacker in a 3-4 alignment. He also has 22 sacks in two years.

Some are excited about pass-rusher Quentin Groves of Auburn, but others aren't so fast to anoint him. He could be another value pick later in the first round who projects as a better pro than Long. However, in this era of win now or be gone, potential can get you fired.

Michigan OT Jake Long has been close to the top of most mock draft boards for some time, but despite his ideal size (6-7, 325), he doesn't possess the natural strength, athleticism or quickness to project to left tackle. He's more of a dominant run blocker who could line up on the right side. One prominent NFL talent evaluator described him as the next Jon Runyan.

Jake Long will still be a very good pro, but teams aren't likely to trade away picks or players for a right tackle. Instead, they could find rising players with growth potential in picks 8-15, like Pittsburgh's Jeff Otah and Boise State's Ryan Clady, players who could develop into cornerstone tackles on the left side. Both could end up in the top 10.

At cornerback, South Florida's Mike Jenkins is only now becoming a playmaker, but his tackling skills are under question; Leodis McKelvin of Troy struggled early against top competition at the Senior Bowl but has moved up the draft boards because of his Senior Bowl performance; and Kansas' Aqib Talib does not tackle well and isn't a physical player.

Virginia Tech junior Brandon Flowers, who came out early because of the lack of an elite corner in this class, is talented but still raw by NFL standards and has to test well to advance in the corner pool.

So who will step into one of those top five spots? Could it be a running back?

Arkansas' Darren McFadden has the early lead, but there is still a lot to learn about the young man -- and remember, six teams passed on Adrian Peterson before the Vikings scooped him up last year. Is McFadden better than Peterson? Scouts have been impressed by another underclassman, Rashard Mendenhall of Illinois, but is he top-five material?

Teams could pass on taking a back early in this draft because it is such a deep class at that position. Knowing this is a deep running back draft, many veteran free agents have signed their deals early, looking to get into a spot before they have to compete with a high draft choice.

The same kind of downward pressure affects the wide receiver position. Take a look at the free agent wideouts that are or are expected to be available: Bernard Berrian and his Chicago teammate Muhsin Muhammad, Seattle's D. J. Hackett, and Arizona's Bryant Johnson. And don't forget Randy Moss, although the Patriots are going to do everything possible to get him re-signed.

And that's just the top of the heap. Why would a team spend a first- or second-round pick on a rookie when it can have a proven veteran for cash and use a lower-round selection to put a future talent in the receiver group?

They won't. And that is why the combine workouts are so important, both to the players and the teams at the top of the draft.

The Dolphins are hoping for a clear-cut top player to emerge, someone they can dangle as trade bait and add to the "elite five" group that currently includes defensive tackles Glenn Dorsey of LSU and USC's Sedrick Ellis.

This combine needs to start to clear up a number of issues. Is there an elite QB in the class? Is there a lock-down cover corner? Is there a future Pro Bowl pass rusher in the group? And can any of the big receivers run well enough to make a team think it has the next Moss?

NFL pro personnel men are hoping to find those answers in workouts here, but going in there's no strong feeling about what this draft really has to offer at the top.