SCOTTSDALE, Ariz. — The San Francisco Giants released veteran outfielder Dave Roberts on Thursday, a surprise move that could cost them $6.5 million this season.

The 36-year-old Roberts signed a three-year, $18 million contract with the Giants in 2007, but played only 166 games in his first two seasons because of elbow and knee injuries. He entered camp this spring as the fifth outfielder behind starters Fred Lewis, Aaron Rowand and Randy Winn, and young prospect Nate Schierholtz.

"It's a surprising blow. I have to rebound from this. I was expecting to see this thing through. I love the makeup of this ballclub. I really wanted to be a part of things," Roberts said.

The Giants tried to trade Roberts over the winter and again this spring, general manager Brian Sabean said.

"There just wasn't a light at the end of the tunnel for him," Sabean said. "I was honest with him. We wanted to get younger and quicker. That's not his resume. To wait any longer would have been an injustice to our kids. This will also give him a chance to find a place to play."

Infielder/outfielder Eugenio Velez appears to be the prime beneficiary of the move. Velez, a nominal candidate for the starting second base job, has spent most of his time this spring in the outfield and is hitting .267 with a home run. He made a game-saving catch in left field for the final out of a 7-6 victory over Arizona on Tuesday.

"(Velez) appears to be a two-way utility man who can play the infield and the outfield, which is rare. You add to that the speed and the switch-hitting," Sabean said.

Roberts was signed to be a disruptive force at the top of the order but was hampered by health issues. He hit .260 with nine triples and 31 stolen bases in 2007, when he was limited to 114 games because of bone spurs in his left elbow.

Roberts missed the first half of the 2008 season after undergoing arthroscopic knee surgery and appeared in only 52 games, hitting .224 with nine RBIs and five stolen bases. His knee bothered him again this spring. Roberts earned $5 million in 2007 and $6.5 million in 2008.

He is a career .262 hitter in 10 major league seasons, with 243 stolen bases. He has perhaps the most memorable stolen base in Boston Red Sox history, stealing second before scoring the tying run in the last of the ninth inning of Game 4 of the ALCS against the Yankees, a game the Red Sox won in extra innings.

Boston won the next three games to complete a comeback from a 3-0 series deficit, the beat St. Louis for its first World Series title since 1918.

A team that signs Roberts off of waivers would owe him the major league minimum of $400,000, with the Giants liable for the remaining $6.1 million.