KANSAS CITY — Royals rookie right-hander Burch Smith’s struggles continue to mount.

In fact, Smith offered up his shortest starting stint to date in six tries. Smith lasted only 1 2/3 innings and gave up six hits and five runs in a 7-0 loss to the Cardinals on Friday at Kauffman Stadium. The Royals have lost seven of eight.

In his last three starts, Smith has given up 16 runs over 10 2/3 innings and his ERA as a starter ballooned to 9.68. His overall ERA rose to 6.97.

“He just wasn’t sharp,” Royals manager Ned Yost said of Smith. “And they didn’t let him get away with any mistakes. Pitches that caught too much of the plate, they did damage with.”

Smith had difficulty commanding his curveball from the start. Paul DeJong blasted a home run off a 1-2 curveball from Smith leading off the second, DeJong’s 11th this season. After a walk, Smith got two outs but gave up an RBI single to Harrison Bader on another hanging curveball.

“Everything [was off],” Smith said. “I was not commanding any pitches. … I didn’t have anything working, and they were capitalizing on mistakes. They’re good hitters.”

Matt Carpenter followed by ripping a 1-0 four-seam fastball into the fountains in right-center field, and it was 4-0. Yadier Molina then doubled, and that was it for Smith.

Right-handed reliever Glenn Sparkman did a fine job sparing the bullpen, going 4 1/3 innings and giving up two runs.

“My hope at that point was (Sparkman) could give us 3 1/3 innings,” Yost said. “So he did a phenomenal job. And I tried to push him, tried to get a couple more outs out of him, but he was really laboring at that point. He saved us. He allowed us to get through that without having to use half the bullpen.”

Meanwhile, the Royals’ offense sputtered against Cardinals right-handed starter Austin Gomber, who breezed through five scoreless innings.

“His fastball was OK,” Royals outfielder Jorge Bonifacio said. “But his cutter was really good. It would come in and look hittable, and then it’d be right on your hands.”