Tim Hightower hasn’t missed a game because of injury in his three-year career. Now he’ll join Ryan Torain as the main facets of the Redskins’ backfield. (Christian Petersen/GETTY IMAGES)

The Redskins on Sunday agreed to sent veteran defensive lineman Vonnie Holliday and a conditional draft pick to the Arizona Cardinals in exchange for Hightower, a former Episcopal High School and University of Richmond standout.

Third-year back Ryan Torain is penciled in as the Redskins’ starter after he made eight starts last season and rushed for 742 yards and four touchdowns on 164 carries (4.5-yards per carry). But health is a concern: The 6-foot-1, 212-pound Arizona State product has yet to play a full NFL season.

The 6-foot, 222-pound Hightower, meanwhile, hasn’t missed a game in his three-year career. Last season, he started 13 of 16 games and tallied 746 yards and five touchdowns on 153 carries. In addition to durability, Hightower also offers versatility.

“I like everything about him,” Shanahan said. “He’s a good blocker, an excellent runner. He’s been very productive. Last year he averaged 4.8 yards a carry. Just a guy that I’ve watched and I’ve liked.”

Further discussing the team’s running back picture, Shanahan said: “Competition. I think what Tim has done over the last three years speaks for itself, and what Ryan has done the last couple years speaks for itself. Ryan has some competition, hasn’t been able to stay healthy. We believe that we have a back that can do it all: He can run, he can pass-protect, he’s a third-down back. I feel good having him here.”

Said Torain: “Competition is just going to make us better. I know he’s a strong runner, I know he’s been in Arizona. I think he’s a good addition to the team. Got to take every play as an opportunity and just keep working hard.”

In addition to Torain, the Redskins also have second-year LSU product Keiland Williams (primarily a third-down back last season), third-year Clemson product James Davis, rookies Roy Helu (Nebraska), Evan Royster (Penn State) and Shaun Draughn (North Carolina) on the roster.

There had been talk Sunday evening that Holliday would retire rather than report to the Cardinals, but responding to a text message Monday afternoon, Holliday said that notion was untrue and that he will be in camp with Arizona.

Said Shanahan: “I had a great conversation with Vonnie and let him know that I thought it was a great opportunity for him, looking at the depth we have at that position right now and looking at our game plan. I thought it was a heck of an opportunity because Arizona really wanted him. Win-win situation.”