Rob Rang

The competition to be the second running back selected in the 2012 NFL Draft will go from one of the more intriguing second tier topics of this week's Scouting Combine to one of the major stories with news Wednesday that Alabama runner Trent Richardson, the unquestioned top talent at the position, won't be able to perform in Indianapolis. 

Richardson, NFLDraftScout.com's No. 6 rated overall prospect, underwent minor knee surgery a few weeks ago after initially injuring his knee while preparing for the BCS National Championship, according to NFL.com's Jason LaCanfora. 

Though Richardson won't be able to participate in the athletic drills at the Combine, according to the report, he is expected to be able to participate in Alabama's March 7 Pro Day. 

(LaCanfora has since reported via Twitter that Richardson will be working out on March 27, raising questions about his availability for Alabama's original Pro Day.)

Assuming that team doctors don't find reason to believe that Richardson will be troubled by the knee in the future, his stock isn't likely to be impacted, according to a league source who shared his thoughts under the condition of anonymity.

"If the doctors say he's okay, it won't change anything. [Richardson] is an elite talent," the scout wrote in a text message.

Considering the physicality with which he plays, however, the injury certainly will be checked out thoroughly by every team. Richardson suffered a slight MCL tear in 2011 and underwent surgery as a sophomore in high school after tearing ligaments in his ankle.

  Richardson is currently slated to be a top five draft pick by Dane Brugler and I. Our colleague Pete Prisco has Richardson slipping a bit further but still has the Crimson Tide star earning a pick in the top half of the first round. 

Since beating LSU in the BCS Championship, it has been a tough few weeks for several highly rated Alabama players. Prior to news of Richardson's injury, Tide seniors Josh Chapman (nose guard) and Mark Barron (safety) each missed the Senior Bowl due to injuries. Junior cornerback 'Dre Kirkpatrick was arrested (and ultimately had the charges dropped) for marijuana possession.

Richardson finished third in the Heisman voting in 2011 behind only Robert Griffin III and Andrew Luck. He won the Doak Walker Award as the nation's elite running back, rushing for 1,583 yards and scoring 23 touchdowns, including the only touchdown in the BCS Championship Game. 

NFLDraftScout.com currently lists Virginia Tech's David Wilson, Miami's Lamar Miller, Boise State's Doug Martin and Washington's Chris Polk as the other four backs behind Richardson as the top five talents at the position for the 2012 draft.