DENVER -- Oakland starter Brandon McCarthy's MRI on his injury-prone right shoulder showed no structural damage, though it's not yet known whether those results are enough for the hurler to avoid a second disabled list stint.

"Whether or not he's able to pitch Saturday, that's probably in doubt, but I'm not going to rule it out to this point," manager Bob Melvin said. "We'll probably wait another day before we make an announcement on what we'll do Saturday."

Should the A's decide McCarthy isn't ready for the outing, which would mark his second straight missed start, it would make sense for Oakland to DL him, so as to be able to bring up a starter from Triple-A without making another roster move. McCarthy would be eligible to return as early as June 23.

The 28-year-old righty has missed time with the same injury on three separate occasions this season and five times in the past five seasons, including last year, when he was out for six weeks.

Right-handers Graham Godfrey and Tyson Ross are the likely go-to options in the event Oakland needs a starter in his stead Saturday.

Cespedes leaves in second inning of return

DENVER -- The combination of Denver's rarified air and Yoenis Cespedes' raw power could make for quite the sight, and it's one that was set to be on display Wednesday when the A's outfielder started his first game in nearly a week because of a strained left hamstring.

But Cespedes, who was back in his normal cleanup spot and playing left field, lasted less than two innings in his return, after being pulled out of the game in the bottom of the second inning in favor of Jonny Gomes after aggravating the same injury.

"It was as much precautionary as anything," manager Bob Melvin said. "It scared him a little, going down the line, and then when he came in for a ball in left field [he] just wasn't comfortable, so we went ahead and took him out. We just didn't want to press him and make it any worse."

Melvin said Cespedes will not play in Thursday's series finale but could potentially be a designated hitter over the weekend.

Prior to the game, Cespedes said through translator Ariel Prieto that he was "very happy" to be back in the lineup but warned he was not yet back to 100 percent.

"I want to try to control my speed," he said. "I'm going to try to run, and if I can go 100 percent I'll do that. If I have to go 80 to 90 percent, that's what I'm going to do."

"Our training staff felt he ran well enough yesterday to where, we put him in a corner spot and limit the movement a little, and hopefully he can take it a little easy on the bases," Melvin said. "I think we've been pretty careful with him, and I don't think this day is certainly not pushing it."

Melvin to be on coaching staff at All-Star Game

DENVER -- A's manager Bob Melvin quickly scratched his original All-Star break plans when Rangers skipper Ron Washington phoned him with an intriguing offer.

Washington wanted to know if Melvin would join his staff for the 83rd All-Star Game, and his answer came immediately.

"Boy that didn't take that long to accept that," Melvin said Wednesday. "It surprised me, but it's quite an honor being asked to do that. An All-Star Game is a feather in anybody's cap.

"We had some plans, but I made a quick call home and said, 'Look, we need to do something a little differently,' and everyone was on board with that."

Melvin was a member of Bob Brenly's D-backs staff for the National League at the 2002 All-Star Game in Milwaukee that memorably ended in a tie. But being asked to go, rather than forced to, makes this year's journey all the more special for Melvin.

"I've always admired him," said Washington, who also handpicked Royals manager Ned Yost. "He's a solid baseball man. You never hear Bob making excuses. He's doing a good job with the Oakland A's team. Jim Leyland told me when he brought me on to coach in the All-Star Game that if I ever got the opportunity to be a manager in the All-Star Game, I should look around and give opportunities to guys that may not have been in an All-Star Game.

"Bob had something planned with his family and when I called him, he talked to his wife, and she immediately said, 'Let's go to the All-Star Game.' I was happy for that. I gave Bob a chance to be out of it but they wanted to come out to the All-Star Game and I want to have them. That was a good thing."

As for making a bid for his own players to join him at the Midsummer Classic, Melvin said, "There are probably some guys I would recommend to Ron if he wants me to do that. As we get a little closer, maybe we'll start to talk about some names, but I'm a little uncomfortable at this point talking about it, because I don't want to leave someone out."

A's close to signing first-round pick Russell

DENVER -- Oakland first-round Draft pick Addison Russell is close to finalizing a contract with the A's, MLB.com learned Wednesday.

Russell will sign for $2.625 million, which is the assigned value for the No. 11 overall selection, according to a source.

"We are still working out some details," scouting director Eric Kubota said, "but we are optimistic about getting something done."

According to the Pensacola News Journal, Russell will depart Thursday for Oakland, "where he will finalize a multi-million dollar contract and meet team executives and players."

Selected by the A's out of Florida's Pace High School, the 6-foot-1, 190-pound Russell -- advised by agent Scott Boras -- was mulling a scholarship offer to Auburn. But his decision to go pro now has Oakland in position to groom the youngster into the impact shortstop prospect they've been missing for some time.

Russell is said to show plus bat speed and flashes big power to the middle of the field, batting over .500 in each of first three high school seasons and most recently posting a .368 average with seven homers as a senior. He added 30 walks for a .532 on-base percentage.

The A's also announced on Wednesday that they agreed to terms with center fielder Herschel Powell (20th round), right-hander Lee Sosa (26th), shortstop Christopher Wolfe (30th), and first baseman John Wooten (37th).