ALAMEDA -- When the Raiders signed Rashad Jennings in the offseason, offensive coordinator Greg Olson wondered if he would even make the team.
Jennings averaged 2.8 yards per carry last season for Jacksonville, where Olson was the assistant head coach and quarterbacks coach.
"To be honest with you, I wasn't sure how it was going to work, him coming here,'' Olson said Thursday. "For whatever reason, he's a better player here.''
With Darren McFadden likely out of Sunday night's game against the San Diego Chargers at O.co Coliseum, Jennings assumes the role of lead runner.
Jennings is coming off an all-around performance in a 24-14 loss to Washington that included a blocked punt recovered by teammate Jeremy Stewart for a touchdown, 14 rushes for 45 yards an eight receptions for 71 yards.
The majority of his 116 total yards came after contact, with Jennings breaking tackles or dragging defenders for an extra yard or two.
In the first quarter, Jennings caught a swing pass from Matt Flynn well behind the first down marker on third-and-8, made one defender miss and broke two other attempted tackles to gain 12 yards to the 45-yard line. The Raiders eventually scored on the drive to take a 14-0 lead.
"I didn't do enough. We didn't get the win,'' Jennings said. "I stay critical of myself. We were critical of everybody on the offensive side of the ball, trying to nitpick the things we could do to make sure we get out of the games with (wins).''
The day after a game in which he had 22 touches and just as many collisions, Jennings rode his bike to work rather than drive. He's a self-described "fitness nut" who sleeps in a hyperbaric chamber to increase blood oxygen and promote healing. He sees a chiropractor and an acupuncturist.
Jennings does this to be ready when called upon.
"When opportunity presents itself, it's too late to prepare for it,'' Jennings said.
When Jennings arrived in training camp, the Raiders already had McFadden, Stewart and also drafted Latavius Murray in the fifth round out of Central Florida.
Coach Dennis Allen, who describes Jennings as a "thumper," wanted him to be a power back in the Raiders' downhill scheme, a physical complement to McFadden.
Based on what he saw in Jacksonville, Olson wasn't so sure.
Olson said he didn't know if it was a different coaching staff, a new scheme or just a change of scenery, but Jennings made an impression early in Napa with his team-first attitude, his work ethic and his physical style of running. He ended up as McFadden's backup, with Murray going on injured reserve.
"He seems to be a tougher player, a tougher runner than I saw a year ago,'' Olson said. "It's not that he was a poor player by any means, but I just didn't see the physicality that he has shown so far here in Oakland.''
Said quarterback Terrelle Pryor: "He's a stud."
Allen said McFadden's potential absence because of a hamstring strain could mean a combination of Jennings, fullback Marcel Reece and Stewart in the backfield. Jennings' ability as a pass receiver out of the backfield gives the Chargers one more thing to consider.
"I think as an offense, the more you can put on film, formations, and guys making plays, the more you have to prepare for it and put it in the back of your mind,'' Jennings said. "It's about us executing, and we have all the rules to beat any defense.''
San Diego (2-2) at Raiders (1-3), 8:35 p.m. NFL Network, KRON
week 4 breakthrough
With starter Darren McFadden out with injury, backup running back Rashad Jennings had a breakout game in Sunday's loss to Washington. Here is Jennings' 2013 game log:
Week Opp. Car. Yds Rec. Yds
1 @IND 2 2 0 0
2 JAX 4 32 1 2
3 @DEN 0 0 2 15
4 WAS 14 45 8 71