CLEVELAND -- Conor Jackson has become a victim of bad timing.

Absent for four games because of neck stiffness, Jackson quickly lost his starting job at first base to Brandon Allen. Now back in a utility role he served at the start of the year for the A's, he's hitless in his last 21 at-bats and knows he has a limited number of days left to prove his worth as a soon-to-be free agent.

"Obviously, going into free agency, you want to play every day," Jackson said. "That was the biggest thing for me. Now, I'm kind of at a point where I think being versatile is going to help me going into it. But on the flip side, you want at-bats, and the only way to get your numbers up is to get those. I've been through these types of stretches, but I was playing every day, so I had the opportunity to hit my way out of it, and this is a little different situation.

"I knew coming into the year, I was going to have to earn my time, and when I did get the opportunity, I would have to do something. Obviously, the past two weeks, I haven't. I haven't done anything to deserve playing time, so it's frustrating, especially this late in the year."

Jackson, who began Tuesday batting .249 with four homers and 38 RBIs in 102 games, has reentered a right-field shuffle that also includes David DeJesus and Ryan Sweeney. Allen -- batting .305 since his promotion -- is expected to assume everyday first-base duties the rest of the way.

"Conor hasn't got consistent at-bats since his injury," Melvin said. "Up to that point, it was probably his best stretch. He'd been playing every day at first and the production was going, and then he hurt his neck, and Allen came, and it's been difficult for him to get back in there regularly. I don't think he's gotten a hit since. It was a tough period for him, and it continues to be a tough period without the consistent at-bats."

It's one Jackson, having already been through multiple ups and downs in his career, takes in stride.

"The writing's kind of on the wall, and I understand the situation. You've gotta play Brandon Allen every day," the 29-year-old Jackson said. "He's a special talent, and he didn't get the opportunity in Arizona he deserves, but this is going to be a good fit for him. As much as I didn't like it, I understand that side of the game."

Allen could be one of several youngsters taking to the field in September, with callups expected to arrive by the end of the week as rosters expand. That could further limit playing time for Jackson, who is also unsure of where he fits into Oakland's bigger picture. DeJesus, Josh Willingham and Coco Crisp are all free agents at season's end, as well.

Needless to say, Jackson is very open to the idea of exploring the market.

"You have to," he said. "I would be doing a disservice to myself if I don't. There hasn't been any conversation here, but I'm a realist, and I'm looking at my numbers here and the next 28 days. Whether I'm in their plans, I don't know. I love Bob Melvin, I'm a big fan, and I think that's a big drawing point for me and for anybody."

Wagner paid his dues before first callup

CLEVELAND -- Perhaps the wait, all six years in the Minors along with a lengthy travel day Monday, was worth it for right-hander Neil Wagner.

The newest A's bullpen member officially joined the team on Tuesday at Progressive Field in Cleveland, through which he used to ride on a bus as a Class A ballplayer.

Manager Bob Melvin wasted little time getting Wagner into a game, sending him out to pitch the eighth inning of a 6-2 loss to the Indians. Wagner struck out Carlos Santana, the first batter he faced, with a 96-mph fastball. After inducing a groundout by Jerad Head, Wagner allowed the first hit of his career, a single by Jack Hannahan. He righted himself, though, and forced Jason Donald to ground out to end the inning.

"It was pretty cool," Wagner said. "Once I settled down and got into the flow of things a little bit, it was all right. I was overthrowing a little bit, with all the emotions, but I settled in and ended up OK. It's almost a relief to have it over with."

Prior to the game, Wagner, 27, said it was fitting that he was called up to face the Indians, who drafted him in the 21st round of the 2005 First-Year Player Draft. He was traded to the A's last season for cash considerations.

"This ballpark, it always seemed so close but so far," said Wagner. "It's a little strange to be here, a little surreal. Of all the places, this is kind of a full-circle type of situation."

Wagner took the 40-man roster spot of Bruce Billings, who was outrighted to Triple-A Sacramento. Wagner will be utilized in the middle innings, Melvin said, and provide the club with a right-handed long relief option.

"I know he's got a plus-fastball and touches 100," Melvin said. "He's working on his changeup and breaking ball, but his fastball is his best pitch from what I understand, and they like what they've seen so far down there this year."

"My bread and butter is my fastball," Wagner said. "That's my best attribute, I'd say, and the difference between last year and this year has been being more consistent throwing strikes and getting ahead of hitters, so I don't have to throw it 2-0, because in that count, no matter how hard you throw, sitting on that, they're going to crush it. That's been big for me."

Wagner began the year at Double-A Midland before he was promoted to Sacramento on June 25, combining for a 3.26 ERA and .232 opponents' average with 87 strikeouts in 66 1/3 innings, an average of 11.80 strikeouts per nine innings.

He's not only familiar with recent catcher callup Anthony Recker and bench coach Joel Skinner, who served as his Double-A manager in Akron last year. He also knows Cleveland's Tuesday starter, Jeanmar Gomez, who was his roommate in 2009.

"The familiar faces, the familiar setting, it helps," Wagner said.

Worth noting

• Michael Wuertz (thumb) will make his second Minor League rehab appearance on Wednesday and, if all goes well, is expected to return to the big leagues soon after the start of Oakland's next homestand on Friday.

• The A's are sending six players to the Arizona Fall League: right-handers Tyson Ross and Ethan Hollingsworth, catcher Ryan Ortiz, infielder Dusty Coleman and outfielders Michael Choice and Grant Green.

• Scott Sizemore finished Tuesday with 11 doubles this month, which is one short of the Oakland record for doubles in August. Jason Giambi collected 12 in 1999.