Daryl Richardson was surprised when he found out this offseason that longtime NFL running back Steven Jackson was no longer a St. Louis Ram.

But Richardson also knew what Jackson's signing as a free agent with the Atlanta Falcons meant for him.

"It was shocking to hear it, but of course, it means a bigger role for me and an opportunity to step up and have a bigger part on the team," said Richardson, a second-year pro who is one of several backs trying to take Jackson's old spot.

Richardson played a larger part on last year's team than probably he or most anyone else anticipated.

In addition to having Jackson entrenched as the starter, the Rams used a second-round pick in 2012 on Isaiah Pead from Cincinnati. St. Louis picked Richardson, a 5-foot-10, 195-pound running back out Abilene Christian, five rounds later.

Pead was seen by many as Jackson's heir apparent. But Richardson outplayed Pead and his quickness proved to be a nice change of pace to Jackson's battering style.

Richardson played in 16 games and rushed 98 times for 475 yards, an average 4.8 yards per carry. He also had 24 catches for 163 yards.

With Jackson gone, the Rams are looking over all their options at running back. Pead is still in the mix, though he has suspended for the first game for violating the NFL's substance abuse policy. Also looking to enter the mix is Zac Stacy, a fifth-round selection this April from Vanderbilt.

Rams coach Jeff Fisher has not officially named a starter, but he has nothing but good things to say about Richardson.

"I think Daryl came back in great shape," Fisher said. "We got a pretty good idea of what Daryl can do.

"We're going to continue to push him through the preseason and the preseason games, and we expect him to have a productive year for us."

So does Richardson, who wants to prove that he is more than a change of pace player.

"You have to believe you can be an every-down player," he said. "You have to have that mind frame and that mentality."

In the Rams' preseason opener Thursday, a 27-19 setback in Cleveland, Richardson did nothing to hurt himself. He had four carries for 24 yards and also caught two balls for 20 yards.

Still, Richardson is taking nothing for granted.

"I'm just going to play out the competition," Richardson said. "I'm excited about the season and I'm just trying to get better every day."