CLEVELAND -- Scott Servais liked the spot for Rafael Montero. It was a mid-leverage moment with a three-run lead for the Mariners' manager to work the up-and-down reliever in after a mixed start to the season. And after two ground-ball outs, it looked like things were going to end quietly, and that the talk of the day would be Yusei Kikuchi’s seven shutout innings.

But Seattle’s reliever had his biggest spiral of the season, giving up three runs that tied the game and putting Paul Sewald in a tough spot in the 10th. It ended with him surrendering the game-winning run on a throwing error that put Seattle on the wrong end of a 5-4 stunner Saturday at Progressive Field.

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Sewald’s soft toss to Tom Murphy was wide to the catcher’s left, and lead runner Cesar Hernandez made a stellar slide around the tag on the front side of the plate to send the 20,116 on hand into pandemonium.

It was Seattle’s third straight loss, and by far the toughest in this brief stretch.

“There’s no way to put a good vibe around that finish to that ballgame,” Servais said.

Montero now has six blown saves, the most in the Majors. Only one other pitcher, Aaron Bummer of the White Sox, has five.

Montero was seemingly on his way to his eighth save after inducing two weak groundouts, but then the righty walked pinch-hitter Bradley Zimmer and Josh Naylor back to back, gave up an RBI single to Bobby Bradley and a dagger of a two-run double to René Rivera. Jake Fraley saved Montero from picking up the loss by making a running catch into shallow left field for the third out to push the game to extras, but the momentum had already swung heavily.

“He quit attacking,” Servais said. “They threw a pinch-hitter up there with two outs and nobody on. Monty’s got really good stuff, you just have to stay with it. You've got to keep pounding the strike zone there. The only thing that can get you is what got us: the free passes.”

Servais didn’t second-guess himself on the decision to deploy Montero in that moment. As Kikuchi dominated his way through seven innings, the plan was always to install Kendall Graveman for the eighth and Montero in the ninth, given that Graveman was pitching in his first game since May 16 after being activated from the COVID IL on Friday.

Graveman, making his 15th appearance, was tagged for three hard-hit balls (exit velocity of 95 mph or higher) among the four batters he faced, including a 404-foot homer by Hernandez, marking the first run that he’s surrendered all season. He was able to induce an inning-ending double play with some help from a heads-up snag by J.P. Crawford.

There was some obvious -- and understandable -- rust for the right-hander given how much time he missed.

“It wasn't overpowering like we've seen him in the past, but that's expected,” Servais said. “It's been [27] days since he's pitched in a game for us. He was able to get the double-play ball there. He only gave up the one run on the home run, but we'll continue to get him out there and build him up. But it's great to have him back.”

With the Mariners opting to send Keynan Middleton to Triple-A Tacoma earlier this week due to his own struggles, a bullpen that was the Majors’ best in the first month of the season has slowly but surely shown vulnerability.

Montero has a 5.40 ERA after Saturday’s defeat. Rookie Will Vest has an 11.42 mark over the past month, a span of 10 games. Anthony Misiewicz's ERA is 6.55 in that same stretch, thanks to a two-run homer he gave up on Thursday in Detroit. With Graveman, these four are their leverage arms, or at least they were during that dominant April, when the bullpen ranked second in the Majors with a 2.35 ERA. Since then, they have collectively posted a 5.67 ERA, third worst.

“We had it lined up the way we wanted to,” Servais said. “Guys need to execute. We didn't execute today. We didn't just stay after it and bury them. So, no, there's no looking back on that. We had the right guys out there. One out away, one strike away from walking off the field with a W -- we just didn't get it done.”