Samardzija had given up three runs on six hits over 10 innings in his three previous Cactus League outings, but the Rockies topped that in the second inning on Friday.
Chris Nelson led off with a home run and the Rockies loaded the bases on three singles, two of them infield hits. Carlos Gonzalez then cleared the bases with a double to take a 5-3 lead.
"The ball was up all day," Samardzija said. "Against this team, they're pretty free swinging and I'm a power pitcher. If I'm down in the zone, it turns into quick outs. If not, you see a cutter there, it gets fisted out, it gets over second base, things like that. Those balls are down, they're ground balls and you're moving on. I need to make a quicker adjustment. It's just a couple pitches here or there to improve on."
Samardzija, a strong candidate for one of the vacancies in the Cubs' rotation, settled down in the third and retired the side in order.
"It felt great to do that and apply what I needed to do, come out and pound the zone with my fastball and be aggressive," he said.
Samardzija did help himself in the fourth, hitting a tie-breaking RBI single. Geovany Soto belted a pair of two-run homers and added an RBI single for the Cubs.
"That's the other frustrating part is when your offense gives you six, seven runs and you can't capitalize on that as a pitcher, that's not good," Samardzija said.
Cubs manager Dale Sveum named Ryan Dempster the Opening Day starter on Friday. Matt Garza and Paul Maholm also have secured spots in the rotation. What does Samardzija have to do?
"All I have to do is keep pitching," Samardzija said. "I'm very happy with how things are going and how I'm pitching and I'm just going to keep throwing and they'll make the decision when they make the decision."
Randy Wells, Rodrigo Lopez and Chris Volstad are also battling for those spots.
"You need to keep showing them that you're out there improving and getting ready for the season," Samardzija said.
That's something Dempster will probably be reminding Samardzija of. The veteran took Samardzija under his wing this offseason and the two trained together in Arizona, beginning in November.
"If [Dempster] had a day like this, he'd go out and get his work in and take positives from it and take the negatives and learn from it," Samardzija said. "That's what I'm going to do. I'm really not worried about it. It's the way it went. I'm more upset with not making the adjustments I needed to make at certain times."
Sveum has made it known how much he likes what Samardzija has done this spring -- and what he could do in the rotation.
"You never doubt the importance of a 6-foot-6, 230-pound horse on the mound," Sveum said. "Every organization thrives for either developing or somehow acquiring somebody like that."