SEATTLE -- Winning a division crown at the very least necessitates a strong showing at home. And for all the Mariners’ offensive shortcomings through the one-third mark of the season, they’ve turned T-Mobile Park into a home-field haven.

The first-place Mariners pulled away late for a 5-1 victory over the Angels on Sunday afternoon that completed a three-game sweep and capped a 6-1 homestand. They’ve now won 17 of their past 22 at home and are 21-11 overall in their own backyard.

And Sunday’s win underscored precisely why they’ve had such success, particularly on a chilly, rainy day where it was no fun to hit -- at least until late. Seattle continued to play to its pitcher-friendly environment by riding the dominance of its arms, Luis Castillo being the latest to twirl another gem.

“Being at home is probably the best advantage any athlete can have in any sport,” Castillo said through an interpreter. “But being here -- especially in this ballpark with the fans that we have, they really do transfer that energy. And it makes us want to go on the mound and pitch for them.”

The Mariners also advanced to 30-12 when their starter tallies at least six innings. They did so despite walking another tightrope, at least until their final inning at the plate. Luke Raley's 110.8 mph solo homer in the fourth was the game’s lone run production until the eighth, when he drew a bases-loaded hit-by-pitch, immediately after which Mitch Garver ripped a bases-clearing double to create a comfortable cushion.

Moreover, this weekend marked the first time in franchise history that the Mariners starters did not allow a run in each outing of a three-game series or longer, when adding the efforts of Bryan Woo on Friday and Bryce Miller on Saturday.

“La Piedra” struck out six and surrendered more walks (three) than hits (two), largely due to deep counts he labored into early in the outing. He needed 30 pitches to clear the fourth alone, when he fell into a full count to each of his first four batters. Yet Castillo wound up escaping by inducing a pair of popouts, themselves an encapsulation of his entire outing -- the Angels had only two hard-hit balls among their 16 in play against the workhorse.

This is what aces are made of.

Castillo clearly didn’t have his stuff early. His four-seam fastball velocity was down 0.9 mph from his 95.5 mph season average, and he missed wildly with the heater to the glove side, especially against righties. The slider also had little movement before an adjustment encouraged by pitching coach Pete Woodworth.

Yet Sunday’s box score painted the picture of a pitcher who had among MLB’s best outings of the day.

The ability to make mid-game tweaks and/or overcome early issues have defined Castillo’s massive turnaround from a tough four-start stretch to begin the year. After posting a 5.82 ERA in those outings -- all Mariners losses -- he has a 2.01 ERA in his 10 starts since, nine of them quality. That’s the seventh-best ERA in baseball among 49 arms with at least 50 innings in this stretch, and among that group, Castillo has accumulated the highest workload, at 62 2/3 frames.

A bid for his third straight All-Star Game and fourth overall appears to be firmly back on the table.

And for the Mariners overall, things are on the up after they advanced to a season-high seven games above .500 (34-27) in just their 61st game. They didn’t go that far into the green last year until Aug. 5, after 111 games.

But now comes the challenge of extending their home-field successes on the road, where they’re 13-16 this season.

“You've got to hit better on the road and be more consistent,” Mariners manager Scott Servais said. “We have not done that. So we have a lot of season left. We need to get better on the road. But keep the special sauce we have here at home, keep that rolling.”

The first stop on a six-game trip -- which comes after their first off-day since May 16 -- offers a soft landing spot, too, as they head to Oakland, where they were 6-0 last year. But then it’s on to Kansas City, where they had some of their wildest games in 2023, to face a much-improved Royals team.