"You know you're going to have fun and you know you're going to focus on baseball and this group of guys makes it so enjoyable," he said. "It's not that it wasn't fun in other camps, but there's a completely different feel here."
Warren made his Cubs debut in Sunday's 8-3 loss to the D-backs and gave up two runs in the first inning, then retired the side in order in the second. The right-hander, acquired from the Yankees in exchange for Starlin Castro, didn't think he'd faced anyone on the D-backs roster before. And Warren admitted he was a little nervous.
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"Things were moving a little faster than I wanted them to," he said of the first inning. "It's to be expected -- I was a little jittery, anxious to get out there, especially with a new team. Just to get that first inning out of the way was really nice. It was really encouraging for me to go out there in the second inning and settle down and pitch like I know I can."
Being a little anxious is OK, Warren said.
"You're going to have butterflies when you pitch in the regular season, so it's nice to experience that," he said.
Last spring, the Yankees groomed Warren to be a starter, and he began the season in the rotation. In 17 starts, he posted a 3.66 ERA, and he was then shifted to the bullpen, where he compiled a 2.29 ERA in 26 appearances. The right-hander isn't exactly sure what his role is on the Cubs.
"As far as for right now, I think it's kind of up in the air," Warren said. "They sat down in the pre-Spring Training meeting and said, 'We can't tell you what you're going to do now -- you could start, you could be in the bullpen.' Long term, I think they saw me as a starter when they acquired me and they told me that.
"It's a special season for this team and I think we'll see how it plays out," he said. "I don't mind being in either role. I think they understand that and that I can bounce back and forth between the two."
All Warren wants to do is fit in. He's still trying to get to know everybody on the team.
"I know there's a relaxed vibe here," he said. "You feel the confidence coming from guys and that's a good thing. Comparing with the Yankees, that's hard to do. There's just a lot of excitement here. That's fun with the fan base and the guys. Everybody knows how talented this team can be and that's what motivates everybody to come every day and work to get to that point."