SEATTLE -- The credibility behind Chris Flexen’s breakout over the past six weeks continues to grow with each start, and he advanced his positive trend with another dominant outing Sunday, a 4-1 Seattle win over the Rangers at T-Mobile Park.

The Mariners are 11-4 when Flexen starts and 34-36 with everyone else. They are five games above .500 (45-40) and 3 1/2 games out of the second American League Wild Card spot in huge part due to their big find out of Korea last offseason, a player they scouted exclusively on video.

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Flexen limited the Rangers to four baserunners and one run over 81 pitches in six dominant innings, which secured the Mariners’ third straight series win to match a season high. He likely would’ve gone deeper had he not been on a shorter leash due to the four days of rest he was on compared to the standard five in the construction of Seattle's six-man rotation.

That efficiency helped position Drew Steckenrider, Paul Sewald and Kendall Graveman to pitch the seventh, eighth and ninth innings, respectively, over which they allowed a combined one hit to the 10 batters they faced.

Flexen put Mariners manager Scott Servais in as ideal a spot as possible, which was helped all the more by booming home runs from Shed Long Jr. and Luis Torrens that gave the pitching staff the cushion it needed.

“You know he’s going to give you a chance to win the game,” Servais said of Flexen. “He is going to keep you in the ballgame. And I'm really impressed with how he continues to develop. … He attacks. He's really bought into what we believe in here, as far as dominating the zone, going and winning 0-1, 0-0 counts. It's really helped him out.”

Since a career-worst start on May 21 in San Diego, Flexen has a 2.62 ERA and has pitched at least six innings in six of his seven outings. The offensive onslaught from the Padres that night was obviously a turning point from a confidence perspective, but Flexen has also fortified the rest of his repertoire in this stretch while fully embracing the Mariners’ mantra of “dominating the strike zone.”

Flexen threw first-pitch strikes to 16 of his 22 batters for a rate of 72.7 percent on Sunday, raising his season average to 65.2 percent, which ranks among the top 25 of pitchers who’ve faced at least 300 batters this season.

“I think that's the biggest thing that's different, definitely the confidence and trust in myself,” Flexen said. “I think the stuff is still very similar, just more fine-tuned and sharpened now.”

He’s also shown far more polish and conviction on the changeup that wasn’t talked about nearly as much as his curveball and cutter in Spring Training, after he signed a two-year, $4.75 million deal.

Flexen flashed the changeup 11 times against the Rangers, who went just 1-for-5 against the offering. The biggest sequence for that pitch -- and, really, his entire outing -- was the 3-2 count in which he threw it to Joey Gallo up-and-away with two runners on in the sixth inning.

A mistake or mislocation in that moment against one of the game’s elite sluggers, especially with an offspeed pitch, could have tied the game with one swing. And Servais said that Gallo was going to be Flexen’s final batter regardless.

“He did a really good job that at-bat forcing me to throw the changeup up higher in the zone,” Flexen said. “I think he took a lot of good pitches early in that at-bat that I executed really well and he spit on them. And I think we got back in the count with a cutter that he took, and I was missing a little off with the changeup. He forced me up, and I just had the confidence to throw it 3-2 and was able to execute it.”

Flexen is slated to make one more start before the second half, next Sunday against the Angels, and it can’t come soon enough. The cerebral right-hander is now 5-2 with a 1.99 ERA in his home confines.