ARLINGTON -- Luis Castillo was dominant once again with seven innings of one-run ball and six strikeouts, but the Mariners were unable to capitalize on the ace’s performance in a 2-0 loss to the Rangers on Friday night at Globe Life Field.

Castillo, who recorded a career-high 10 strikeouts in his previous outing against Pittsburgh, appeared to ride that momentum into his impressive start against Texas in the opener of a three-game set.

The Seattle right-hander was flawless his first couple of times through the Rangers’ order, and he did not surrender a hit until Robbie Grossman’s single in the bottom of the fifth inning.

Castillo yielded a second straight single to Travis Jankowski, followed by a wild pitch that put runners on second and third with one out. Despite the high-leverage situation, Castillo took a breath to compose himself on the mound, before forcing Leody Taveras and Sandy Leon to fly out to end the inning.

“That was a heck of a pitching performance,” manager Scott Servais said. “Can’t say enough about Castillo. He went out there for seven innings against one of the hottest offenses in the game.

“So, for him to pitch the way he did, I feel bad we didn’t do anything for him offensively.”

Despite the loss, Castillo has been near perfect since his lackluster start to the season. In his past three starts, dating back to May 23, Castillo has compiled 24 strikeouts and allowed just three runs through 19 innings.

During that stretch, Castillo’s ERA has dwindled from 2.97 to 2.55, which is the seventh-best mark among all qualified American League starters. Additionally, his 0.69 ERA since May 23 is the fourth best in the Majors.

“I feel phenomenal,” Castillo said through interpreter Freddy Llanos. “Thank God that I’ve had the help that I’ve had. I’m just going to continue to do what I do best and that’s hopefully what we continue to see.”

Castillo also spoke of the importance of his secondary pitches, and how he’s been using them to keep opposing batters off balance.

"They have been working really well for me,” he said. “The only difference is we’ve been putting more time in with the pitching coach [Pete Woodworth] and my confidence has grown, which is why I’m having the results I do.

“That’s what secondary pitches are for … to keep batters guessing and confused about what’s coming next.”

Castillo certainly has opponents guessing, all right, as his slider continues to mystify batters. Opponents are carrying a meager .167 batting average against Castillo’s slider.

Over his last three starts, his slider has been especially effective, as batters are 1-for-8 (.125 batting average) with three strikeouts against the offspeed pitch.

“He’s got really quality stuff,” Servais said. “He plays with no fear. He goes right on the attack -- no matter who’s in the box.

“Again, the Rangers are having a good year offensively, and he went right out there tonight and did a nice job.”

On the other side of the ledger, after scoring just six runs in a three-game series against the Yankees, the Mariners’ offense was anemic once again vs. Texas.

Seattle mustered just three hits (all singles) and had a runner in scoring position just once, when Julio Rodríguez swiped second base in the fourth inning.

It was his 11th stolen base of the season, making Rodríguez one of four MLB players with 10+ home runs and 10+ stolen bases this season -- joining Ronald Acuña Jr., Josh Lowe and Bobby Witt Jr.