SAN FRANCISCO -- Games like the Giants' 7-2 loss Tuesday night to the Colorado Rockies might seem meaningless, given the team's non-contending status.

But the endless evaluation process lends significance to virtually every inning, particularly as the Giants continue to judge which players might be able to help them in 2009.

The bullpen is a particular source of interest for San Francisco, since it's likely to be one of the areas general manager Brian Sabean attempts to strengthen this offseason. Except for All-Star closer Brian Wilson, none of the relievers has displayed wall-to-wall consistency, although all of them have enjoyed stretches of competence.

This was rookie right-hander Sergio Romo's turn to make an impression. Romo worked 1 2/3 perfect innings, his second scoreless appearance in as many games and third in a row since being recalled Aug. 16. During his first stint with the Giants, Romo posted a 4.41 ERA in 16 appearances -- which was somewhat deceiving, since his ERA was 2.35 until he yielded four runs in his final outing before returning to Triple-A Fresno.

Indeed, Romo's first taste of the big leagues only strengthened his belief in himself.

"I think the only difference is more of a feeling that I can pitch at this level," he said. "It's never been a confidence issue. It's more stuck in my head that I'm meant to do this."

Romo's control should bolster his case. Maintaining the remarkable precision that earned him MiLB.com's Class A (Advanced) Relief Pitcher of the Year award last season, Romo has walked only four batters while striking out 21 in 20 innings. He thus stands out on a Giants staff that has amassed the National League's second-highest walk total.

"I'm a big believer that the first-pitch strike is the best pitch," Romo said.

Manager Bruce Bochy has noticed.

"He's commanding his pitches and mixing it up," Bochy said. "When you do that, you're probably going to have success up here."

Basic baseball economics also favor Romo, 25. He's not eligible for salary arbitration, unlike left-hander Jack Taschner and right-hander Tyler Walker, who have shared the setup role this season. Granted, Taschner and Walker probably will be bargains compared to any competent reliever on the free-agent market, where a bullpen specialist can command approximately $4 million annually.

"It's kind of hard to believe that last year I was in A ball," Romo said. "I feel proud and privileged to be in the situation I'm in."

Romo received some fresh competition after the game, when the Giants optioned right-hander Matt Palmer to Fresno and recalled right-hander Osiris Matos from Triple-A. Matos was 0-2 with a 4.05 ERA in 13 appearances for the Giants during July and early August, although he might return to the Minors once left-hander Jonathan Sanchez is activated from the disabled list to start at Colorado on Monday.

"This is a great opportunity for all these young guys, and that's why they're up here, so we can get a good look at them," Bochy said. "You're hoping that they show that they don't want to go back to the Minor Leagues."

Palmer (0-2) couldn't avoid that fate. He allowed four third-inning runs and disappeared as the Rockies added a run in the fifth. Colorado essentially settled matters by scoring twice off Taschner in the seventh.

The Giants grabbed a temporary 1-0 lead in the second inning as Rich Aurilia and Randy Winn doubled off Colorado starter Jorge De La Rosa (7-7). The Rockies overshadowed that with their big third, which featured two-run singles by Garrett Atkins and Chris Iannetta.

San Francisco responded with an unearned run in the fourth, but Colorado countered in the seventh as Ian Stewart and Troy Tulowitzki stroked RBI singles. The Giants fell to 10-9 in their stretch of 20 consecutive games that ends Wednesday with ace Tim Lincecum on the mound.

"Maybe the guys are dragging a little bit, but I'm sure we'll bounce back tomorrow," said Aurilia, who went 3-for-4. "We've got Timmy out there and hopefully we'll come out swinging the bats."