ARLINGTON -- Right-hander Tyson Ross was on the move again Friday, this time back to Triple-A Sacramento following a brief third stint with the A's.

Ross was optioned less than 24 hours after he was handed the loss in Thursday's 7-6 defeat to the Rangers, who tagged the pitcher for five runs on eight hits in four-plus innings. The A's called up first baseman Chris Carter to take his roster spot, allowing manager Bob Melvin to keep a taxed eight-man bullpen on hand for the remaining three games in Texas.

In 12 starts with the A's, Ross is 2-8 with a 6.35 ERA and nearly as many walks allowed (30) as strikeouts garnered (35) in 62 1/3 innings. Left-handers were batting .354 off him, and his .277 opponents' average against right-handers wasn't encouraging, either.

"He needs to get deeper in games," Melvin said. "He needs to find a secondary pitch that's a bit slower, we believe. His fastball velocity, if it's 92-93, and his slider is 87-88, that's probably not a big enough gap for a starter. But I think his slider was better in the times we saw him here recently. Sometimes his rhythm can be a little bit off, and therefore teams will run on him a little too much."

With Ross back in Sacramento, the A's will need a starter for Tuesday's home contest against Boston, and the answer may already be in the clubhouse, as Melvin said Bartolo Colon could be an option for the start. It marks the day Colon is eligible to be reinstated from the disabled list, and the team is likely to decide on his availability for the outing after his bullpen Saturday.

Right-hander Graham Godfrey, currently stationed in Sacramento, has posted numbers similar to Ross in five appearances (four starts) for the A's this season, going 0-4 with a 6.43 ERA. But he could potentially be back Tuesday, should Oakland keep him from making his scheduled start with the River Cats on Saturday.

A's call up former top prospect Carter

ARLINGTON -- Each of Chris Carter's four stays with Oakland has been a disappointment, but the A's youngster is hoping the fifth time proves to be the charm.

Carter, once considered the club's top prospect, was called up on Friday to make his season debut with the A's, following two stints in each of the last two seasons. He started at first base against Rangers lefty Matt Harrison, batting seventh, and will platoon with Brandon Moss -- hitting just .125 over his past seven games -- at the position going forward.

It would seemingly serve the A's well to give Carter a lengthy look at the plate in order to decide where he fits into the organization's future. The 25-year-old has played in parts of eight Minor League seasons, collecting a combined .283 average, .378 on-base percentage and .913 OPS, yet he's hit just .136 with three home runs and a .174 OBP in the big leagues.

"I think, like anybody, you make your own opportunities at the big league level," manager Bob Melvin said. "If you come in, you knock the door down and force us to put you into the lineup. I think that's what everyone aspires to do in the big leagues. It just hasn't happened for him yet up to this point."

"That's always the thought process," Carter said. "I know what to expect now. I don't have any excuses."

Most recently, Carter was batting .279 with 12 home runs and 53 RBIs in 72 games with Triple-A Sacramento. He appeared in 47 games at first base and, more recently, made several starts at designated hitter while splitting time in the field with former big league regular Daric Barton, who's hitting .253 for the River Cats.

"I've been coming along a lot better now," Carter said. "I went through some struggles a few weeks ago but came out of it and have been feeling good lately. Before, I was swinging at everything again, which I know I can't do.

"It's always nice to be back. I've been waiting for this moment all season, and I'm ready for it."

Melvin noted Carter has made small adjustments at the plate since he was last in Oakland, making better use of the lower half of his body rather than just relying on the power from his hands. Yet, Melvin also noted the bigger change for Carter in the big leagues will likely have to be a mental one.

"I think the physical attributes are all there," Melvin said. "You watch him take batting practice and you see how far he hits the ball. In spring, we've seen him do some good things, too. Just maybe you create a little doubt in your mind at the big league level that you haven't been able to break through and stay."

Worth noting

• Josh Reddick received a scheduled day off on Friday, with the right-handed-hitting Jonny Gomes starting in right field against Harrison. Elsewhere in the lineup, Derek Norris received his first big league start at designated hitter, one night after hitting his second home run in five games with the A's.