"Sounds like he was a little rusty," manager Walt Weiss said. "He had a tough first inning but it looks like he settled in after that."
"I was a little antsy and was overthrowing in the first inning," Butler told the Modesto Bee. "About halfway through the second inning, I dialed it back and through the fourth I was able to maintain that level of intensity and actually hit some spots."
Overall, Butler surrendered two hits, two walks and struck out two but Weiss was more concerned with the fact that Butler felt fine physically after the outing.
"With the rehab guys, the most important thing is that they come out of it healthy and they get their work in," Weiss said.
Butler is expected to make his next rehab start with Triple-A Colorado Springs on Thursday. Weiss has confirmed Butler is "absolutely" an option to rejoin the Rockies on July 22 when the team first requires a fifth starter out of the All-Star break.
Cody Ulm is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.