Carlos Villanueva, who was placed in the rotation while Arrieta rehabbed from a sore shoulder, will move back to a bullpen role. Further roster moves to accommodate these transactions will be made at a later time.
Arrieta made five rehab starts throughout April, most recently for Double-A Tennessee on Saturday, when he threw 44 pitches in a final tuneup. He followed that with a side session at Great American Ball Park early Monday, after which he was given clearance to rejoin the rotation.
"I'm feeling really strong," Arrieta said. "I feel like since I didn't have a normal Spring Training, it's kind of a different process, kind of being at the end of my Spring Training right now. I feel like I'm further along than that process would initially allow. Those are good things. I feel really strong and I'm ready to get going."
Ballplayers are creatures of habit, as they say, so it's not at all surprising that the random nature of Minor League rehab assignments didn't exactly appeal to Arrieta. Returning to the routine environment of a Major League rotation, and knowing exactly where he'll be and what he'll be doing each day, is much more to his liking.
"It was a pain throwing in Minor League games every three, four, five days," he said. "Not having a set routine, traveling all over the place, throwing an inning here, an inning there ... it's nice to be done with that and be back here with the team every five days taking the ball and competing."
Arrieta doesn't believe he'll be on any type of pitch count as he eases his way back in and said he could go as high as 90 to 100 pitches if needed. But any hurdles he may encounter, however unexpected, won't detract from his confidence. Arrieta is definitive about where he thinks he fits in to the Cubs' equation this year.
"I know what I'm capable of," he said. "The work that I put in -- I think the sky's the limit. I think I can be a guy that this team can rely on for a long time. I showed a lot of that last year and I'm confident that I could pick up where I left off and be even better than that. I'm very confident."
Alyson Footer is a national correspondent for MLB.com. Follow her on Twitter @alysonfooter. This story was not subject to the approval of Major League Baseball or its clubs.