KANSAS CITY — This was not what the Royals or right-hander Matt Harvey were looking for in his third start this season.

Harvey, signed as a non-roster free agent on July 28, had shown promise in his first two starts, displaying a 94-95 mph fastball with late life in the first two innings of those outings before faltering in the third.

But on Tuesday at Kauffman Stadium, Harvey essentially had nothing working in a 10-1 loss to the Indians. Harvey lasted just 1 1/3 innings and gave up six hits and five runs — including three homers.

The 10 batted balls against Harvey averaged a 95.9 mph exit velocity, per Statcast, which classifies anything 95 mph or higher as hard-hit.

“It just kind of all fell apart pretty quickly,” Harvey said. “It felt this week that I had figured some stuff out, and I was pretty excited to go out tonight and show that. But clearly, it didn’t happen.

“I couldn’t really [get a] feel for anything. Everything was just spinning. It was extremely frustrating to let the guys down and struggle that much and really hurt the bullpen. I’m not doing my job. I’m taking it the hardest. It’s something I take a lot of pride in, so this is very hard.”

It marked the eighth time in Harvey’s career that he gave up three long balls in a single game, including seven since he pitched the Mets to a World Series berth in 2015.

Francisco Lindor smacked a 2-2 fastball into the right-field seats in the first. Later in the inning, Franmil Reyes powered a slider over the right-center-field wall. And in the second, Roberto Pérez blasted another slider for a two-run homer to right.

The only good news for the Royals was a peek at the future. Right-hander Carlos Hernández, 23, made his big league debut, replacing Harvey in the second.

Hernández, 6-foot-4, 250 pounds, is the Royals’ No. 12 prospect per MLB Pipeline. He had not appeared in any games above Class A Lexington, but he was plopped on the 40-man roster last fall to protect him from the Rule 5 Draft. He’s started 41 of his 42 Minor League outings and projects as a potential starter, boasting a four-seamer that ranges from 95-99 mph.

Hernández relieved Harvey with two on and one out and got two quick flyouts.

“Very impressive,” Royals manager Mike Matheny said. “A real bright spot for us. Bringing him in with a couple of guys on, I don’t know how you couldn’t be impressed. He attacked the strike zone, threw breaking balls for strikes. He got swings and misses. He didn’t try to overthrow, for the most part.”

Hernández threw 3 2/3 scoreless innings, gave up two hits and one walk and struck out two.

“He kept things under control and had a great tempo,” Matheny said. “He got the ball on the rubber, and he had a plan and he executed. About as good a debut as you could hope to have.

“Every time these guys step on the mound for the first time, there’s so much that goes into it, the work they’ve done, and all the support from all over. And then he just took over.”

Hernández was given the ball from his first big league strikeout of Roberto Pérez in the third inning. He said it will be kept in his living room.

“I felt really nervous [at first],” Hernández said through interpreter Luis Perez. “But it went away after the first pitch.

“Right after the game, I got to talk to my mom and send text messages. Then I got a chance to talk to my wife. Just very appreciative to get that opportunity.

“I’ve worked really hard for this moment, and to get that moment was really a lot of work.”

Hernández’s mom’s reaction to his phone call?

“She cried,” he said, smiling.