DENVER -- This isn't rookie pitcher Casey Kelly's first trip to Coors Field, and when he takes the mound on Sunday, it won't be the first time he's done so, either.

Well, sort of.

Last September, after he had completed his season with Double-A San Antonio, Kelly and fellow pitchers Joe Wieland and Robbie Erlin joined the team in Colorado for the final two weeks of the regular season -- not on the roster, but as bystanders charged with taking in as much as they could while watching veteran players go about their business.

"I think it was valuable for those guys," said Padres manager Bud Black.

No more so than for Kelly, who tossed six scoreless innings in his Major League debut on Monday against the Braves. His second start will come at Coors Field, where he tossed a simulated game last September.

Asked about his experience last September, Kelly said it was beneficial for him to learn and watch.

"I think it was a great experience, because you didn't come in here having to worry about playing that day," Kelly said. "You could see how everyone goes about their business. And with the starting pitchers, you could watch whoever was starting for the whole day, when they go into their meetings, going over scouting reports ... really just how they go about preparing themselves.

And while he was still nervous before his start against the Braves, he felt better prepared for what might occur, thanks in large part to his unofficial time in the big leagues late last season.

"It was huge. You learn so much by watching," Kelly said. "You get to sit and listen to the veteran guys who have maybe faced a hitter hundreds of times. You watch what the hitters are doing, too. And you start thinking about what you want to do to them."

Headley sorry to see hot August come to end

DENVER -- It's not the number of hits, home runs or RBIs that Chase Headley will remember most about his torrid stretch at the plate during the month of August.

It was more those opportunities he missed out on, in what was easily the most productive month that he has had in his big league career.

"It was funny, I was talking to [hitting coaches Phil Plantier and Alonzo Powell] about it and to be honest with you, I feel like it could have been a bigger month," Headley said.

"I felt like I've squared up a lot of balls that didn't end up being hits. That's going to happen when you're hitting the ball well."

After Friday's 5-4 victory over the Rockies, Headley finished with at .306 with 33 hits in August. He led the league in RBIs with 31 and tied for the league lead in home runs (10). Headley's RBI total is the best by a Padres player in one month since Ryan Klesko had 40 in May, 2001.

"I felt pretty good for most of the month," Headley said.

The most hits Headley has had in one month is 33, which occurred in August, 2009. He had 32 hits last August and last June. But he wasn't nearly the run-producer that he's become this season.

"I have had months where I've had the same amount of hits, but I don't think that in the big leagues I've put together a month like that," Headley said.

Stauffer undergoes surgery on right elbow

DENVER -- Pitcher Tim Stauffer, limited to five innings this season because of a balky right elbow, had surgery on Friday to repair the flexor tendon.

"It was what the doctor anticipated, reattachment of muscle to bone," Padres manager Bud Black said Friday. "The doctors expect a full recovery. He'll be ready to go by Spring Training.

The procedure was performed by Dr. Heinz Hoenecke and Dr. Lorenzo Pacelli at Scripps Clinic.

Stauffer was working his way back to the big leagues and was set to make his second rehab start with Triple-A Tucson earlier this month when he experienced soreness in his right shoulder. Stauffer then returned to San Diego to be reexamined.

Stauffer was in line to start on Opening Day until the final week of Spring Training, when he first started to feel discomfort in his elbow. He started the season on the disabled list, but he was activated on May 14 in time for a start in Washington.

Stauffer experienced soreness in his elbow -- in his flexor tendon bundle -- late in that outing against the Nationals. He allowed four runs (three earned) in five innings and eventually landed on the disabled list again on May 18.

Stauffer will likely be a non-tender candidate this winter. He made $3.2 million this season and was the sixth-highest paid player on the team behind Huston Street, Carlos Quentin, Orlando Hudson, Jason Bartlett and Chase Headley.

Short hops

• Street was to pitch Friday for Single-A Lake Elsinore, but he was scratched after he experienced pain in his strained left calf while jogging. It doesn't appear like much of a setback for Street, who will meet the team in Los Angeles on Monday.

"We'll talk about his status then," Black said.