"It was a good experience, facing those hitters," Coleman said.
He's being considered for either the rotation or the bullpen for the Cubs, who have one opening left. Cubs manager Mike Quade said Friday that Andrew Cashner has made the team but had yet to designate his role. If Cashner goes to the bullpen, there's one opening in the rotation. If Cashner is a starter, there's an opening in the 'pen.
Coleman said he'd do whatever the Cubs want.
"I like to say I have a rubber arm," he said. "I love being out there whenever they need me. Yeah, it's Spring Training and you're still trying to get in shape, but eight pitches [Wednesday], and I was fine. I could go [Thursday, Friday], whenever they needed me."
What impressed the Cubs was how the right-hander handled the A's lefties.
"That's a plus because they can trust you no matter what the situation is," he said. "If the bullpen needs a rest, and you're in the bullpen, it gives them a lot more confidence, especially against a lefty like [Matsui], who's proven in the big leagues."
It's taken a little time for the 23-year-old pitcher to develop that. Last season, he was 10-7 with a 4.07 ERA at Triple-A Iowa and was called up to the big leagues for the first time. He went 4-2 with a 4.11 ERA in 12 games, making eight starts.
"For me, it's just confidence," Coleman said. "Last year I started to struggle a little against lefties. Being able to execute the changeup early and the fastball in late, if you can do that, you'll have success against lefties. Being a left-handed hitter, I know how tough it was to stay in on a fastball that tails back or a changeup away. I'm using that to my advantage."
Being a hitter has helped him become a better pitcher.
"I know how hard it is to be a hitter," he said. "It gives you that extra confidence knowing these guys up there aren't perfect. It's definitely an added confidence boost."