OAKLAND -- Brent Rooker reaching 20 home runs seemed like an inevitability earlier this season, based on a scorching first month as one of MLB’s top hitters that helped the A's slugger earn his first career All-Star selection.

Of course, baseball is often a game of peaks and valleys, something Rooker knows from experience. After hitting .358 with nine home runs in April, the outfielder/designated hitter has gone through his ups and downs in the ensuing months.

It may have taken a bit longer than originally anticipated, but Rooker finally reached that milestone in Sunday’s 12-1 loss to the Orioles at the Coliseum, slugging homer No. 20 in the seventh inning by sending a 391-foot solo shot off Nick Vespi into the second deck in left field.

“It’s a cool one to get,” Rooker said of reaching 20 homers for the first time as a big leaguer. “I obviously would like to hit a few more and eclipse that milestone in future years, but it’s a good place to start. A good achievement and something cool to look back on.”

In a down year where most of the focus for this rebuilding A’s club comes in identifying players who can help them beyond 2023, Rooker’s emergence continues to be one of the more positive developments. Along with leading the team in both homers and RBIs (51), Rooker also carries a .798 OPS.

“He went through a tough stretch and I think right now he’s swinging the bat really well,” A’s manager Mark Kotsay said of Rooker. “He’s taking good, quality at-bats. He’s determined to be a part of that lineup on an everyday basis, and he’s showing that right now.”

Over his last nine games, Rooker is 10-for-33 (.303) with two home runs and two doubles.

“I feel pretty good,” Rooker said. “Swing feels good. I feel like I’ve got a good plan most at-bats and am able to go up there and execute it a good amount of the time. … Swing and approach-wise, I feel pretty solid.”

Rooker’s milestone was a bright spot on a day in which the A’s were officially eliminated from the American League West title race and swept for the 17th time this season, tying the Oakland record set in 1978.

Outscored 28-7 by the Orioles, owners of the best record in the AL, the A’s got a glimpse at a club that has provided somewhat of a rebuilding blueprint for them to follow. 

It was only a couple of years ago that the Orioles endured a 110-loss season in 2021, similar to the track the A's find themselves on this season. Since then, however, Baltimore has turned a corner with an influx of young talent headlined by stars like Adley Rutschman and Gunnar Henderson, who fell a single shy of the cycle on Sunday.

With top prospects such as Zack Gelof, Tyler Soderstrom and Lawrence Butler now big leaguers, the A’s are hopeful that they will be able to follow a similar path back to playoff-contending baseball in the coming years.

“You look across the diamond and you know where that team was a few years ago,” Kotsay said of the Orioles. “You have to believe that this process we’re going through, we’re going to get through this difficult time and pursue what they’ve accomplished. That’s bringing this nucleus of young guys in and building around them to get where they are at, and that’s the best record in the American League right now.”

Speaking of Gelof, Sunday was yet another chapter in his early breakout. The rookie second baseman collected a pair of singles, marking his 10th multi-hit performance through his first 31 career games. Gelof is the first A's player with 10 multi-hit games in his first 31 career games since Daric Barton had 12 from 2007-08.