OAKLAND -- When the Mariners acquired catcher Omar Narváez in November, they believed they were sacrificing the power of Mike Zunino, who was traded to the Rays, for Narvaez’s excellent on-base percentage of .366 in his three seasons with the White Sox.

Narvaez not only has maintained that OBP at .368 this year, he has unleashed significant punch as well, with 16 home runs and a .504 slugging percentage in his first 80 games.

The 16 home runs -- with two coming in Tuesday’s 9-2 loss to the A’s -- have already eclipsed the 12 he hit in 221 games with the White Sox, where his slugging percentage was .379.

“That’s probably the one thing that has surprised us the most about his game,” manager Scott Servais said. “I thought he was a guy that would probably hit 10-12 in a good year, which is a good year for a guy catching as much as he is.”

Narvaez says he’s not trying to hit homers, but he certainly isn’t turning them down.

“I don’t really try to do too much,” he said. “I’m just trying to hit line drives. If it comes, it comes. If it doesn’t, I’m still hitting line drives.”

That approach has helped Narvaez hit five homers already this month, tied for the third most in the American League behind only the Angels' Mike Trout and the Astros' Yuli Gurriel going into Wednesday’s action.

“He continues to make adjustments with his swing,” Servais said. “He’s got the ability to get the ball in the air. And when you can pull balls in the air, you’re going to get good results. It’s worked out well for him.”

While the Mariners’ offense has gone into a funk in recent weeks, Narvaez has been one of the few shining lights. Since June 14, he has hit .350 (28-for-80) with 16 runs, two doubles, seven homers, 15 RBIs and a 1.042 OPS in 25 games.

While Narvaez isn’t the defensive presence that Zunino was, he’s working hard on that part of his game. And the irony is that he has far exceeded Zunino’s power. Zunino is hitting just .179/.234/.330 with five homers and 20 RBIs in his first 53 games with the Rays, while Narvaez has a .297/.368/.504 line with 38 RBIs.

Worth noting
• Right fielder Mitch Haniger has been cleared by the doctor to resume some light activity as he recovers from surgery on his ruptured testicle, but Servais said it will be a slow process after Haniger had a setback upon his initial return two weeks ago.

"He still has some issues and is feeling some pain on certain days, so we have to be careful how fast we go with him,” Servais said. “He can’t do a whole lot of heavy lifting. He’s got to be very careful. It’s a serious injury.”

• Servais said Sam Tuivailala threw well and came out of his first game off the 60-day injured list with no problems, though he allowed three ground-ball singles and two runs in the eighth inning of Tuesday’s loss in his first MLB game since rupturing his right Achilles tendon last August.

“It’s a struggle when guys have major injuries like that, not just physically but what you go through mentally to get back on top of it,” Servais said. “He wasn’t happy with giving up a couple runs, but he feels fine physically and is out here throwing the ball around today. He feels good.”

• Servais, a former catcher, said he’d never seen an umpire get hit in the head with a bat as happened with Brian O’Nora in Tuesday’s game, a situation that turned controversial when O’Nora called a questionable ball four on what Marco Gonzales thought was an inning-ending strikeout of Marcus Semien, before Matt Chapman and Matt Olson broke the game open with home runs in the fifth inning.

O’Nora took himself out of the game after that inning and didn’t work in Wednesday’s series finale, either.

“I think Brian was trying to get in close, getting on the inside part there with the catcher,” Servais said. “Domingo [Santana] takes a big hack with a big follow-through. He got hit pretty good. I sat back there with those guys for plenty of years and understand they take a beating. I certainly respect the job they do.

“But when something happens, you’re probably best removing yourself from the game and turning it over to somebody else. Obviously that didn’t happen, it was a big pitch in the game. But Chapman and Olson did the damage afterward.”

• Outfielder Mac Williamson cleared waivers and was outrighted to Triple-A Tacoma, so he remains in the Mariners' organization after being designated for assignment on Monday to open a roster spot for Tuivailala’s return.