GLENDALE, Ariz. -- The A's on Monday officialized a one-year deal with veteran right-hander Trevor Cahill, formalizing their reunion with the pitcher they drafted as an 18-year-old back in 2006.
"It's exciting," said Cahill, now 30. "Just glad to be back in the uniform and definitely somewhere I'm comfortable, so signing this late I think it'll make the transition pretty easy."
Cahill, guaranteed $1.5 million by the A's, has been going through the motions of a pitching program on his own for several weeks in the Phoenix area, building up to the equivalent of three innings. He said he threw a bullpen session in front of A's coaches on Monday and could see game action by the end of the week.
"I feel like I'm built up pretty good," he said. "I haven't faced Major League hitters yet, but I've been doing the best I can to stay ready."
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Starting is the job Cahill prefers, but it's unclear if he would be Opening Day rotation-ready, leaving open the possibility of a bullpen role. The nine-year veteran has done both in his career, which includes stints with six teams.
"We've added him for starting depth, and we'll see where we're at," A's manager Bob Melvin said. "We're going to get him some innings here as quickly as we can before spring's over. I saw him throw a bullpen today. He looked good, looks like he's in good shape. We'll see what we have for him."
At the conclusion of the 2011 season, when Melvin's interim title was shed, Cahill was traded with Craig Breslow to Arizona in exchange for Jarrod Parker, Ryan Cool and Collin Cowgill.
"I thought I was going to be there a lot longer, and then the trade happened," Cahill said. "I loved playing for Bob, and I loved my whole experience in Oakland."

Cahill began the 2017 season with the Padres, pitching to a 4-3 record and a 3.69 ERA in 11 starts before he was shipped to Kansas City at the non-waiver Trade Deadline in a package that also included Ryan Buchter, who is also now in green and gold. Cahill posted an 8.22 ERA in 10 games for the Royals (three starts) while battling injuries.
"I felt at the beginning I was pitching as well as I ever have, and then I kept getting hurt and pitched through some stuff and it just didn't really work out the second half," he said. "This offseason, I spent a lot more time working on shoulder stuff, and my arm's felt better than it ever has, so I'm excited to go out there and take the ball every five days or every other night or whatever it is."
The A's are operating with an unproven rotation that will likely necessitate Cahill's starting services at some point this season, even if not at the start.
"I'd love to start," Cahill said. "I think I'm still able to start, and hopefully that's where I can help the team out the most, but I've pitched in all different kinds of situations and roles, so I just want the ball, and whenever that is is fine with me."