MESA, Ariz. -- The A’s do not expect to know the full makeup of their outfield until next week. However it shakes out, manager Mark Kotsay made it clear that Esteury Ruiz will be a part of that group.

“Esteury was told that he will be on the Opening Day roster,” Kotsay said prior to Friday’s 12-0 loss to the White Sox at Hohokam Stadium. “He’s had a great camp. Another young talented player that we aggressively pursued and acquired in a trade this offseason. He’s performed through Spring Training. But more than that, the track record through the Minor Leagues aligns with his opportunity to be on this roster.”

Ruiz is a player whom the A’s coveted in years past, finally landing him this offseason as a key part acquired from the Brewers in a three-team deal that sent Sean Murphy to the Braves. Now rated Oakland’s No. 6 prospect, the 24-year-old outfielder entered camp viewed as a frontrunner to make the roster. Still, performance was going to play a factor in that outcome. Entering Friday, he was 13-for-40 (.325) with a .879 OPS, three doubles and a home run this spring. His 14 RBIs were also tied for the Cactus League lead.

The run tool is without question Ruiz’s most tantalizing trait. He brings legit 80-grade speed, which was on full display in 2022 when he led the Minor Leagues with 85 stolen bases as part of a breakout campaign that saw him slash .332/.447/.526 with 16 home runs, 33 doubles, two triples and 65 RBIs over a combined 114 games at Double-A and Triple-A.

With MLB’s new rules for 2023 encouraging more stolen-base attempts, Ruiz becomes even more valuable for an A’s club looking to improve an offense that ranked last in most statistical categories last season. This spring, Ruiz has been quite active whenever he’s on base, swiping six bags in seven attempts.

“We’ve run more in Spring Training,” Kotsay said. “It’s no secret that Ruiz, when he gets on the basepaths, wants to run. We’ll at times have to curtail those opportunistic times when he feels like he needs to steal third or second. But overall, I think stolen bases are going up in general.”

The next step for the A’s will be figuring out how much playing time they will give Ruiz to begin the season. He’s played exclusively in center field this spring, though Cristian Pache is considered an elite defender at the same position and is among the group of outfielders still contending for an Opening Day roster spot, along with corner outfielders Conner Capel and Brent Rooker.

“At this point, we’re still assessing the outfield,” Kotsay said. “There’s still opportunity and decisions to be made out there.”

Muller’s final tuneup
Kyle Muller did not have the ideal final tuneup before the regular season on the day he was officially announced as Oakland’s Opening Day starter.

Allowing four runs on six hits in a 30-pitch first inning, Muller regrouped and settled in for the next couple of frames before running into trouble again in the fourth, with his final pitch a two-run homer surrendered to Romy Gonzalez. Reaching his targeted pitch count of 90, Muller allowed eight runs (four earned) on 10 hits and a walk with five strikeouts in 3 2/3 innings.

“I turned my phone off this morning because I knew they were going to announce it today,” Muller said. “Now I’ve got to answer to them. It sucks that I had to pitch like [that] on the day that news broke, but it’s part of it.”

Kotsay didn’t put too much stock into the outing from a numbers perspective. For him, the most important development is that Muller came away feeling healthy ahead of his first career Opening Day nod, which will come Thursday night at the Oakland Coliseum against Shohei Ohtani and the Angels.

“No concern at all,” Kotsay said. “For these young guys that are going to take the mound [for us], the only way they’re going to get better is if they learn from these types of outings. For me, the biggest thing is he came out healthy and got his pitches to 90. Spring Training, you have days like this.”