"It's kind of a role I've embraced and been in in the past," Arrieta said. "I was the guy in college and enjoyed that role. The college game is completely different, and the season is structured a completely different way, but I still understand that role.
"I've been willing and able and ready to accept those responsibilities for a while. The performance pushes me more in that direction than I expected."
Arrieta will make one more start before the All-Star break, as he will get the ball on Friday as the Cubs wrap up the first half with a three-game series against the Braves.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.