MESA, Ariz. -- When a pitcher is making adjustments in his repertoire during Spring Training, as Sean Manaea is, it’s best to overlook the results and focus on the progress.

Manaea, projected to be a key member of Oakland’s starting rotation, has been working on refining his slider and changeup. They’re not yet finished products, but if the 6-foot-5, 245-pound southpaw opens the season with even a modicum of command with either delivery, he could become truly formidable.

“Everything went really well today,” Manaea said Friday after yielding four runs on four hits in three innings while striking out six during Oakland’s 11-5 Cactus League loss to the Cincinnati Reds. “I felt like I made some competitive pitches and they took some good swings on them.”

Oakland bench coach Ryan Christenson, who served as acting manager while Bob Melvin attended to personal business back home, praised Manaea’s effort, saying, “He made a couple of mistakes, but he was crisp."

Worth noting
• Matt Olson, typically a slow starter who nevertheless bashed 36 homers last year, hit his first Cactus League clout, a two-run drive in the first inning off Reds starter Wade Miley.

• The A’s trimmed their spring contingent to 51 by optioning right-hander Daulton Jefferies to Triple-A Las Vegas and reassigning six pitchers to Minor League camp: left-hander Donnie Hart and right-handers Ben Bracewell, Parker Dunshee, Ian Gardeck, Brian Howard and Zach Lee.

Up next
The A's will take part in an American League West contest on Saturday in the Cactus League, as lefty Jesus Luzardo starts against the Mariners. First pitch is set for 12:05 p.m. PT in Peoria, Ariz. Luzardo is scheduled to be followed by Jake Diekman, T.J. McFarland and J.B. Wendelken. Former A's right-hander Kendall Graveman is set to start for Seattle. The game can be seen live on MLB.TV and heard on Gameday Audio.