But more important than anything was the fact he felt no pain.
"It felt completely fine, and that's the one thing we wanted to push," Cook said. "Sitting down between innings, getting back up and getting loose again usually is what aggravates it the most. But I had no pain. I felt great and was real happy to be out there throwing."
Cook, the Opening Day starter for the Rockies, hopes to end the season in the same rotation. He posted an 8-7 record and 4.12 ERA during the regular season and has been mentioned as a potential Game 4 starter against the Diamondbacks in the NLCS, which starts Thursday night at Chase Field.
He joined the team in Phoenix on Wednesday night.
"They have some decisions to make, and I'm sure they'll talk to me, either [Wednesday night] or tomorrow and let me know what their decision is," Cook said. "I think I'm ready and would love to be part of it, but we have a team that is playing really good baseball right now."
The Rockies have cooked up a 17-1 record heading into the NLCS opener, beating the Padres in a one-game playoff for the NL Wild Card spot and then sweeping the Phillies in a best-of-five series.
Question is, are the Rockies ready to bring back Cook?
O'Dowd wore a poker face on Wednesday.
Asked if he was impressed enough by Cook's outing that it warranted a spot on the 25-man roster, the GM said, "I'm not going to comment on that. We'll talk about it as a group."
As for his overall impressions of Cook, O'Dowd said, "It looks like he's healthy. He's healthy. He's definitely healthy. His velocity was fine, and that's all I'm going to comment."
Cook breezed through the first three innings, retiring the first eight batters he faced. The D-backs had two infield hits in the fourth but never came close to scoring.
The biggest trouble of the day came in the sixth inning.
Cook needed 24 pitches to get through the inning, which included two more infield hits and a solid line drive to right field that scored a run.
"It was a good test," he said. "Twenty-four pitches in an inning always is a good test. I told the trainer that I really hadn't thrown out of the stretch, and that [inning] gave me a chance to do that and also use my slide step."
He escaped with just one run being scored and then worked a one-two-three seventh, striking out the final batter he faced.
"I could have gone eight, but we already had decided on a pitch count of between 85 and 90," he said. "There was no reason to go back out there for five pitches."
So he departed, got something to eat and gave the organization something to chew on.
"It's now wait-and-see," he said.
Rosters must be submitted to MLB by 11 a.m. MT on Thursday.