Position Series: Running Backs

Dallas Cowboys quarterback Tony Romo hands off to running back Lance Dunbar (25) during warm ups before an NFL football game against the Washington Redskins, Monday, Oct. 27, 2014, in Arlington, Texas. (AP Photo/Brandon Wade)

Dallas Cowboys running back Joseph Randle (21) runs to the end zone for a touchdown during the second half of an NFL football game against the Chicago Bears Thursday, Dec. 4, 2014, in Chicago. (AP Photo/Charles Rex Arbogast)

Dallas Cowboys running back DeMarco Murray (29) takes a handoff from quarterback Tony Romo (9) during an NFL football wildcard playoff game against the Detroit Lions on Sunday, January 4, 2015 at AT&T Stadium in Arlington, Texas. The Cowboys defeated the Lions, 24-20. (AP Photo/James D Smith)

Dallas Cowboys running back Lance Dunbar carries the ball against the Seattle Seahawks in the first half of an NFL football game, Sunday, Oct. 12, 2014, in Seattle. (AP Photo/Elaine Thompson)

Dallas Cowboys running back DeMarco Murray (29) tries to elude a tackle attempt by Washington Redskins strong safety Phillip Thomas (41) on a fourth quarter run during the NFL week 17 regular season football game against the Washington Redskins on Sunday, Dec. 28, 2014 in Landover, Md. The Cowboys won the game 44-17. (AP Photo/Paul Spinelli)

DeMarco Murray, corredor de los Cowboys de Dallas, penetra la línea de golpeo durante el partido del domingo 21 de diciembre de 2014, frente a los Colts de Indianápolis (AP Foto/Tim Sharp)

Dallas Cowboys running back Joseph Randle (21) is tackled by Indianapolis Colts linebacker Jerrell Freeman (50) during an NFL football game on Sunday, December 21, 2014 at AT&T Stadium in Arlington, Texas. The Cowboys defeated the Colts, 42-7. (AP Photo/James D Smith)

FILE - In this Jan. 11, 2015, file photo, Green Bay Packers outside linebacker Clay Matthews (52) tackles Dallas Cowboys running back Joseph Randle (21) during the second half of an NFL divisional playoff football game in Green Bay, Wisc. Clay Matthews is one of the NFL's most visible linebackers. Bobby Wagner's profile is much lower _ except when leading one of the NFL's most feared defenses. (AP Photo/Mike Roemer, File)

Dallas Cowboys running back Joseph Randle (21) runs 40 yards for a touchdown during an NFL football game against the Jacksonville Jaguars on Sunday, November 9, 2014 at Wembley Stadium in London, England. The Cowboys defeated the Jaguars, 31-17. (AP Photo/James D Smith)

Dallas Cowboys running back DeMarco Murray (29) runs against the Green Bay Packers in an NFL divisional playoff football game Sunday, January 11, 2015 at Lambeau Field in Green Bay, Wisconsin. The Packers defeated the Cowboys, 26-21, to advance to the NFC Championship game. (AP Photo/James D Smith)

Dallas Cowboys running back Lance Dunbar (25) runs during the first half of an NFL football game against the San Francisco 49ers Sunday, Sept. 7, 2014, in Arlington, Texas. (AP Photo/Tony Gutierrez)

Dallas Cowboys running back Lance Dunbar (25) carries the ball during the first half of an NFL football game against the Washington Redskins in Landover, Md., Sunday, Dec. 28, 2014. (AP Photo/Richard Lipski)