SEATTLE -- As the Mariners are still looking to heat up their cool bats on this season-opening homestand, errors like the pair on Tuesday loomed large in a 5-2 loss to the Guardians at T-Mobile Park.

Mitch Haniger had a chopping grounder bounce off his glove in right field that allowed José Ramírez to race all the way home from first base to break a scoreless tie in the fourth inning. Then in the fifth, third baseman Josh Rojas made a wide throw to first baseman Ty France’s left on a bunt attempt by Steven Kwan that plated another.

In between, and in the at-bat just after Haniger’s miscue, Luis Castillo surrendered a two-out homer to Bo Naylor that gave Cleveland enough breathing room, given that Shane Bieber was spinning his way to nine strikeouts in his second scoreless effort of the season.

“You've got to play clean, unless your offense is really clicking and can overcome it,” Mariners manager Scott Servais said. “Our offense is not really clicking yet, so every out is so important.”

After Bieber departed, the Mariners made things interesting with two runs in the seventh, when Rojas -- who was at the center of much of Tuesday’s action -- chipped an RBI single past Ramírez at third base to end the shutout bid. Then, J.P. Crawford hit an RBI groundout, but Julio Rodríguez skied a flyout to deep left field for the third out.

Seattle had six hits against Bieber, and seven of their 14 in play off him were hard-hit (95 mph exit velocity or higher), including four in the first. But the 2020 American League Cy Young Award winner then settled in, stranding each of the three doubles that the Mariners recorded over the rest of his six total innings.

Like Boston did so effectively against the Mariners over the weekend, Bieber went for the jugular with his secondaries, with six of his punchouts on his slider and knuckle curve. Just as effectively, he worked the edges, especially in deep counts.

The Mariners are now hitting .160 with a .412 OPS against offspeed pitches, the fourth- and third-lowest marks in MLB.

The offense has had some clutch moments, headlined by Rodríguez’s walk-off on Saturday, but they’ve also struggled to create momentum. And though this stat certainly won’t hold, each of their three victories have been by one run -- underscoring how vital an offensive uptick could be.

“There were some good at-bats, but again, at the end of the night, the strikeouts -- they will get you,” Servais said. “That guy can strike you out. He's got really good stuff, that does happen. But that is an area that we need to get better at.”

Beyond Bieber, Tuesday was shaping up as a pitchers’ duel with Luis Castillo, who struck out six of his first 11 batters and looked dominant, spotting the four-seamer much better than on Opening Day, landing the slider for strikes and generating a few gnarly whiffs on the changeup, a pitch that took a step back in 2023.

“It's very important, I mean, instead of having two pitches, I have a third one that's very effective,” Castillo said through an interpreter. “And today, I felt like the location was there.”

But the at-bat that yielded Haniger’s error proved to be a turning point, especially given that Castillo had worked Will Brennan into an 0-2 count then labored through three straight fouls before Cleveland’s right fielder yanked a changeup at the bottom of the zone for the two-out knock. Then, the homer to Naylor was a 96.3 mph heater out of the zone but in on his hands, just enough for him to ambush for a 383-foot, pull-side blast.

“I've always said it -- it's not how you begin, but it is how you finish,” Castillo said.

In just a few short bursts, Castillo was on the verge of another scoreless frame but instead left with a three-run deficit that wound up being too tall for Seattle’s bats to overcome. The play that ended his day was also within Rojas’ territory -- a fly ball that sliced over the third baseman’s head in shallow left field for a single.

“I just got a bad read off the bat,” Rojas said. “I actually thought it was over my head more. So he hit it, I turned I actually turned my back all the way to turn in and get a sprint going. Then I looked back up and it was tailing and dying to the other side.”