This is not about a lack of stamina or durability, and it is not about a mysterious drop in velocity.

Mike Minor's outing on Tuesday afternoon was more about not being able to execute his best strikeout pitch at a crucial moment. Minor’s changeup is the weapon that made him an All-Star last season and it was the one that hurt him the most in his latest frustrating start.

Minor gave up a first-inning grand slam to Wil Myers on a two-out, 2-2 changeup and the Rangers lost their third straight with a 6-4 loss to the Padres at Globe Life Field. The Rangers remain in third place in the American League West, 2 1/2 games behind the second-place Astros.

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Minor also gave up a two-run home run to Jurickson Profar in the fourth and the left-hander fell to 0-4 with a 6.94 ERA after five starts. Rangers starters are a combined 5-9 with a 4.55 ERA after 22 games overall.

“Got to be better,” Minor said. “There is nothing I can do. I can’t sit here and pout. I feel like I am right there. I feel like some of the pitches aren’t there. Not as consistent as I would like, [but] good enough to not give up six runs every time. I feel like I need to go deeper in the ballgame. I just have to be better.”

Minor plays his fastball and changeup off one another. He likes to bust the fastball inside on right-handed hitters and throw the changeup away, so having an erratic fastball may play into it.

“I feel like it's messing with my head a little bit,” Minor said. “I need to go out there and pitch and get big league guys out, rather than worry about my velocity. So yeah, the velocity plays a role. I sit there and almost bang my head against the wall thinking, 'What am I doing wrong? Why is the ball not moving? Why am I not throwing harder?' Because I feel like I put in the work every week.”

Bench coach Don Wakamatsu, filling in while Chris Woodward was serving a one-game suspension, said Minor showed his normal velocity and there were no signs of any physical issues.

“We saw the velocity … 93 [mph] was the top,” Wakamatsu said. “He was fairly strong, the changeup was fading on him. He just got himself in trouble early. That’s a good-hitting club. If he gets the changeup … that was the one pitch that got him.”

The first inning began with Padres leadoff hitter Trent Grisham reaching on an infield single. Fernando Tatis Jr. and Manny Machado each followed with singles to load the bases.

Minor got Eric Hosmer to hit a high chopper back to the mound and made a nice athletic play to get the forceout at home. Minor then struck out Ty France for the second out. That brought up Myers, who entered the game 0-for-6 with two strikeouts in his career against Minor.

Also, going into the game, opponents were hitting .179 (45-for-252) with just four home runs against Minor’s changeup since the start of the 2019 season. Myers’ grand slam was No. 5.

“It’s my best pitch,” Minor said. “It’s kind of like my equalizer … but right now, it’s not playing the same. It doesn’t have the same movement that I would like. I’m not sure what’s going on, but trying to work on it.”

Minor said the changeup just feels different and it was hardly consolation when he was able to strike out Myers with the pitch in the third. Minor struck out the side that inning.

“It’s not moving the way I want it to,” Minor said. “It doesn’t feel the same out of my hand and that’s something I’m working on. I have thrown some good ones and gotten some strikeouts on them. It’s not where it needs to be.”

Profar’s home run gave the Padres a 6-0 lead in the top of the fourth. The Rangers scored four in the bottom of the inning, including a three-run home run by Joey Gallo. But they managed just one hit the rest of the game.