49ers sign RB Westbrook

Hours after trading disgruntled defensive end Kentwan Balmer to the Seahawks, the 49ers made an even bigger splash, signing coveted free-agent running back Brian Westbrook.

Westbrook had been linked to the Denver, St. Louis and Washington over the offseason. Saturday, ESPN’s Chris Mortensen called the Rams frontrunners. Sunday, Redskins coach Mike Shanahan reiterated his interest in the versatile veteran. But it was the 49ers who swooped in and signed Westbrook to a one-year contract.

NFL.com’s Jason LaCanfora reported that he will earn a base salary of $1.25 million, and could receive as much as $2.5 million.

Westbrook, 30, has fought through numerous injuries during his eight years with the Philadelphia Eagles, including a series of concussions that knocked him out of eight games a year ago.

When healthy, he has proven to be one of the NFL’s most dynamic offensive performers. Westbrook rushed for a combined 2,550 yards in 2006 and 2007, and three times he has caught more than 70 passes in a season. He is the Eagles’ all-time leader in yards from scrimmage, a category in which he led the NFL in 2007, with 2,104.

Frank Gore is still expected to start at halfback for the 49ers. But the team needed depth after backup Glen Coffee decided to retire this week after only one NFL season. Rookie Anthony Dixon was a revelation in rushing for 100 yards at Indianapolis on Sunday, but is viewed as raw when it comes to technique and fundamentals. The 49ers apparently wanted a safer option, and Westbrook was it.