OAKLAND -- Tyson Ross is back in Oakland under entirely different circumstances from his previous recall.

Ross filled in for starter Bartolo Colon, who had just been suspended for violating baseball's substance policy, in his last appearance.

When the A's optioned him to Triple-A Sacramento the next day, he was asked to go to the bullpen.

"It will be more of a length-type situation," A's manager Bob Melvin said. "With his stuff, his best chance is in the bullpen."

He's started 13 games for the A's this year, with a 2-9 record and 6.45 ERA. Ross allowed five runs on nine hits in six innings in his last Major League outing. His next appearance will be in relief.

Ross appeared in two games, allowing four runs, three earned, on four hits and a walk in two innings of relief work with the River Cats. He was 6-2 with a 2.99 ERA in 15 games, 13 starts, overall with the River Cats.

Rickey stops by A's clubhouse before game

OAKLAND -- Hall of Fame player Rickey Henderson was in the A's clubhouse before Monday's game with the Angels, making the rounds and chatting with several people.

"We love having him around as much as we can," A's manager Bob Melvin said. "He goes around and watches all our teams and he does a great job when he's here."

Henderson, who holds Major League records in stolen bases and leadoff home runs, was animated while telling stories and most observers were caught up in his infectious giddiness.

"It's always nice to have prominent players like him, Hall of Fame players, around," Melvin said.

Sizemore a long shot to return this season

OAKLAND -- Scott Sizemore, who suffered a left ACL tear early in Spring Training, continues his rehab work, though it remains a long shot he will return this season.

"It's tremendous just to watch him out there working so hard," A's manager Bob Melvin said. "He's coming along."

Sizemore can swing the bat and takes ground balls.

Jordan Norberto (left shoulder tendinitis) is eligible to come off the disabled list but has not been able to start a throwing program.

Eric Sogard (strained back) is playing catch but is not allowed to run yet. Dallas Braden (left shoulder surgery) had another surgery performed on his shoulder in the last four days and will be on the shelf for the foreseeable future.