PHOENIX — On a bright spring Sunday afternoon, the Rockies played lost and found.

They lost lefty starter Greg Smith to what he called a “dead arm.” But they likely found their fifth starter in lefty Franklin Morales.

“This was the best he’s thrown this spring,” catcher Yorvit Torrealba said. “He threw his fastball to both sides of the plate, and in his last two innings his curveball was outstanding.”

Though Morales gave up a two-run, walk-off homer to Chris Denorfia that lifted the A’s to a 7-6 victory, that was a small matter in the spring-training scheme of things. In five innings, Morales gave up just two runs on three hits. His presence on the mound was excellent and his confidence rebounded after he gave up 10 runs in five innings in a minor-league game last week.

“I think I pitched pretty good today because of my fastball,” Morales said. “I threw the pitches where I wanted to.”

Hurdle wouldn’t confirm whether Morales would now become the fifth starter, pointing out the schedule enables the Rockies to go with a four- man rotation into the third week of April. However, Hurdle had been impressed by Morales’ development this spring, despite the roller-coaster nature of that development.

“Franklin pitched very, very well today,” Hurdle said. “I’m very impressed with the development he’s made this spring. He’s gotten a little bit better each time out.”

For Smith, who was part of the Matt Holliday trade with Oakland, it’s been a spring of frustration. Sunday, his fastball clearly wasn’t up to major-league standards.

“As a player, you know when something is not where it should be,” he said. “The location wasn’t bad, the mechanics weren’t bad. I just didn’t have the velocity I should have.”