SEATTLE -- The curious case of Andrés Muñoz continued for the Mariners after another tough outing that contributed to a 4-3 loss to the Red Sox on Friday night at T-Mobile Park.

The flamethrowing right-hander entered in a tied game in the top of the seventh inning, but he immediately found himself playing catchup after his first batter, Bobby Dalbec, took him deep for a 374-foot home run into Boston’s bullpen. The solo homer came against Muñoz’s slider, a pitch that opposing hitters were just 6-for-43 against with 20 strikeouts entering the night.

Muñoz then hit the next batter, Rob Refsnyder, with a 101 mph fastball that slipped away in a 2-2 count. He gave up a single to Rafael Devers on a 98.7 mph heater in the next at-bat, which put runners on the corners, then induced a 6-3 double play to J.D. Martinez on a 100.7 mph fastball that erased the traffic but plated a run, which proved decisive.

Seattle’s bats had chances, with 12 at-bats with runners in scoring positions, but the Mariners manufactured only three hits in those moments and stranded 10, including the tying run on third base and the would-be winner on second when Adam Frazier lined out to end the game.

Muñoz threw 21 pitches, induced nine swings and generated only one whiff, another outing emblematic of his inconsistent first full season in the Majors. Muñoz possesses arguably the best pure stuff in Seattle’s bullpen, and on some nights, he looks electric. But on others -- despite his velocity ranking in MLB’s 100th percentile, per Statcast -- opposing hitters have had a knack for timing him up, like on Friday.

“Andrés has been very aggressive with his fastball,” Mariners manager Scott Servais said. “We've seen that of late. He just didn't get the slider where it needed to go."

It was an all too familiar feeling for Muñoz, albeit not as dramatic, given that against this same team on May 22 in Boston, he gave up a game-tying RBI single to Kiké Hernández then a walk-off grand slam to Franchy Cordero to cap a four-game sweep.

Friday’s outing raised Muñoz's ERA to 5.31 over 22 outings. Fifteen of those appearances have been scoreless, and eight hitless. Yet by the numbers, it’s been the highest-stakes moments where he’s stumbled most, according to Baseball-Reference.

Muñoz by leverage in 2022, entering Friday
High: .450/.560/.900 (1.460 OPS), 3 HRs, 3 K's, 4 BBs, 25 PAs
Medium: .143/.143/.286 (.429 OPS), 1 HR, 9 K's, 0 BBs, 21 PAs
Low: .242/.286/.273 (.558 OPS), 0 HRs, 13 K, 2 BBs, 35 PAs

“We see some nights where it's just electric, unhittable,” Servais said. “And other nights, the command is just a little bit off, and those are the nights it's a little bit of a challenge for him. We love the stuff, love the pitcher. He's just learning, that’s part of it.”

Each night, Servais and his coaching staff map out where each reliever will best fit based on matchups, their rest entering the outing and much more. Despite his struggles, Muñoz’s power-pitching profile is typically the more conducive matchup for an opposing team’s best sluggers -- which is precisely why he was installed to face the Red Sox's Nos. 9-1-2 hitters.

Yet, Boston’s loaded lineup was the latest to square up Muñoz's heater. He throws the second-hardest fastball in the Majors at an average of 99.6 mph, just behind Cleveland’s Emanuel Clase (99.7 mph) among 652 players who’ve thrown a pitch this season. Entering the night, opposing hitters were batting .452 and slugging .774 against it, and though the slider was the culprit for Dalbec’s homer, the Red Sox were still all over Muñoz's heater.

Muñoz has typically been on one end or the other of his fastball-slider pendulum this season, which may also be a contributing factor to opposing teams being able to better game plan against him.

“Obviously, we’ve faced him before,” Red Sox manager Alex Cora said. “We know what he does. And he just hung a slider. ... We’ve faced him twice already, and we’ve done pretty good against him. That’s 101, 100 [mph] with that slider. But we dominated the strike zone, and we scored runs against him.”

Muñoz, who preferred not to speak postgame, is 23 years old and has only 44 big league innings under his belt, a reminder that he’s still green and learning to navigate big league lineups.