One thing that won't happen: Westbrook isn't going to unseat Frank Gore as the team's starter. Nor will he share the workload in the Niners backfield.
"The one thing I wanted him to know about our team is that Frank Gore is our running back," 49ers coach Mike Singletary said. "Frank is still the man.
"I told him, ‘There will be some times when Frank has to take a blow. At those times, I want you to be ready.'"
The 49ers signed Westbrook to a one-year contract Monday, filling the roster spot left vacant when running back Glen Coffee announced last week he was quitting football. Coffee submitted his retirement paperwork with the league office Monday.
Westbrook said he'll wear No. 20, the same number he wore at Villanova.
According to several reports, Westbrook's deal is worth $1.25 million, with another $1.25 in incentives. Although the St. Louis Rams and Washington Redskins had shown interest, Westbrook began leaning toward the 49ers after he spoke with Singletary last week.
"My first conversation with coach was purely about winning," Westbrook said. "Coach felt they wanted to bring in a guy who could help them win now. I feel like I'm that guy. Urgency is my biggest thing. I want to win now.
"I want to bring in my leadership ability, my ability to catch the ball out of the backfield and my ability to run the ball as well. Frank is the man. I respect his game a lot. I'm going to push him as much as I can."
How Westbrook is worked into the game plan is up to offensive coordinator Jimmy Raye. Although rookie Anthony Dixon ran for 100 yards Sunday in the Niners' preseason opener against the Indianapolis Colits, Singletary was tepid about his performance afterward. Dixon has been slow to learn blocking schemes, which is what promoted the move to sign Westbrook.
"I would not want to put Dixon in that position right now," Singletary said. "You wouldn't want to put your quarterback in a situation with a running back that doesn't totally understand pass protection."
Singletary's next chore will be convincing Gore to take a breather in games and let Westbrook assume some of the rushing load, a task Singletary has acknowledged won't be easy. The Niners want to avoid having Gore wear down as the season stretches into December.
"I told Frank that we'll see how it goes," he said. "Frank is a guy who wants the ball, and I understand that. I want him to understand that we want him as long as we can have him."
Westbrook, who spent the first eight years of his NFL career with the Philadelphia Eagles, missed time last season after suffering two concussions. It was believed his career was in jeopardy, but he insisted he was told by doctors that he was in no more danger of a serious head injury than any other player.
The 49ers had a busy day Monday, trading defensive lineman Kentwan Balmer to the Seattle Seahawks for a sixth-round draft pick earlier in the day. Balmer had been absent from training camp since last Wednesday after being given two days to take care of personal matters.
INJURY UPDATE: Singletary said tight end Vernon Davis suffered a sprained right knee against the Colts and is day to day. Rookie wide receiver Kyle Williams has a sprained big toe and will be re-evaluated in a couple of weeks. Also, cornerback Will James is out 4-6 weeks with a sprained ankle. Linebacker Travis LaBoy, out with a concussion, is expected back this week. And linebacker Ahmad Brooks (lacerated kidney) will start riding a stationary bike this week, Singletary said.