Is there a first-rounder in the RB class?

The 2013 NFL draft could be a historic one for running backs, and not in a good way.

At least one running back has been taken in the first round every year since the AFL and NFL drafts merged in 1967, but that streak appears to be in serious jeopardy.

It's still possible that a back could shoot up the board during the pre-draft evaluation process or a team could reach for a back in the draft, but it's not looking good based on the current situation.

South Carolina's Marcus Lattimore was squarely in the first-round mix before suffering a gruesome, season-ending knee injury, and the next two backs on the board are underclassmen who carry late-second-round grades. They could decide to stay in school with the hope of boosting their stock next season.

What exactly is keeping this year's top prospects out of the first-round discussion? Let's take a look, but let's remember that a back doesn't have to be a first-rounder to make an impact at the next level. Just ask Washington Redskins rookie Alfred Morris, a sixth-round pick who is tied for third in the league with 1,106 rushing yards through Week 13.

North Carolina's Giovani Bernard (Grade: 82)

The biggest concern with Bernard is his ability to handle a heavy workload and stay healthy over the course of a grueling NFL season. He has just average size (5-foot-10, 205 pounds) and tore an ACL in the fall of 2009. Bernard has some wear on his tires, averaging more than 18 carries per game the past two seasons and taking more hits as a receiver and punt returner.

However, he is atop our running back board because of his versatility. Bernard is quick, shifty and instinctive as a runner, making the most of his blocks and flashing the ability to create even when he doesn't get a defined seam. His size will hinder his ability to anchor in pass protection, but Bernard is an effective receiver who catches the ball well and produces after the catch. Finally, he has the burst and vision to make an impact on punt returns.

Michigan State's Le'veon Bell (Grade: 80)

Bell checks in at 6-2 and 242 pounds, and he has to prove to scouts he is quick enough to be productive at the NFL level. Backs his size can succeed in the NFL -- just look at Atlanta's 244-pound Michael Turner -- but Bell's burst will be closely monitored during pre-draft workouts.

Still, Bell's size means he is tough to bring down. He can bounce off or power through would-be tacklers, and there's a lot to like about Bell's ability to exploit cutback lanes and bounce runs outside when necessary. It's his third-down ability that makes him an intriguing Day 2 prospect, though.

His size allows him to hold up well in pass protection, and he is an above average route-runner for his size with 76 career catches and the ability to line up in the slot at times.

Wisconsin's Montee Ball (Grade: 77)

Experience is a valued asset in most job interviews, but not for running backs, who have short NFL shelf lives.

Ball has 900 career carries at Wisconsin, and his decision not to enter the 2012 draft will likely end up hurting his stock in 2013. He has stayed healthy for the most part, but that is a lot of pounding. Teams will also closely evaluate the concussion Ball sustained in an off-field incident.

Still, he is one of the most efficient runners in the country, with above average instincts, the discipline to follow blocks and the ability to get vertical as soon as he locates a seam. At 5-11 and 210 pounds, Ball doesn't have elite power, but he runs hard and picks up yards after contact. He is quicker than fast but has enough burst to rip off chunks of yardage when he gets a seam.

Clemson's Andre Ellington (Grade: 75)

Ellington is an undersized back (5-9⅜, 195) who has had problems staying healthy and doesn't have the power to push the pile in short-yardage situations. There are also concerns about his vision and anticipation.

However, after watching several tapes and seeing him play in person at Boston College this season, one word comes to mind: effort. Ellington may be small, but he has above average balance and is always fighting for yards after contact. He is fast enough to make defenses pay when he hits a seam out of the backfield, after the catch or returning kickoffs.

Oregon's Kenjon Barner (Grade: 74)

He is also on the smaller side (5-9⅛, 186) for a running back prospect, doesn't show great power between the tackles and has been nicked up at times. The reason Ellington grades slightly higher is that Barner is slightly smaller and has had ball-security issues.

Barner is at his best in space, and it's not just about his shiftiness or above average top-end speed. He shows above average instincts in terms of recognizing where pursuit is coming from and makes the most of his open-field blocks. He is never going to be a great pass-blocker who can anchor against blitzing linebackers, but Barner is an above average receiver for the position.