KANSAS CITY — Royals left-hander Danny Duffy was cruising along Tuesday night, carrying a lead into the sixth, and looking everything like the pitcher he had been over the last seven starts, a stretch in which he posted a 2.68 ERA.

But Duffy’s season bugaboo — his secondary pitches — bit him in the sixth. Duffy hung a changeup to Cleveland’s Yan Gomes, who plopped it into the left-field bullpen for a grand slam with none out in the sixth, and that carried the Tribe to a 6-4 win at Kauffman Stadium.

The Royals have now lost five straight and 23 of 27.

Duffy has given up 12 home runs this season off his slider and changeup — six on each. Conversely, opponents have hit only three home runs off his four-seam fastball.

“I feel really good about them,” Duffy said of his secondary pitches. “I honestly feel really good about them. But I got beat on my offspeed today. I’m not going to sit here and say I made good pitches. I didn’t. I gave up six runs. I didn’t pitch well.”

Duffy fell in trouble in the sixth with his fastball, walking Edwin Encarnacion and then hitting Brandon Guyer with a four-seamer. After an infield hit loaded the bases, Duffy stayed away from the four-seamer to Gomes and left a 1-0 changeup on the outer half of the plate. Gomes didn’t miss and the Tribe went up 6-4.

Where did Duffy want the changeup?

“Not there,” Duffy said. “I wanted it down, and not over the middle of the plate where he could tattoo it. I wouldn’t have gotten into that situation had I not hit Guyer. He’s a guy who’s seemingly right on the plate and I let one get away. Walked the first guy, just a weird inning.

“All that could have been avoided if I hadn’t made a bad pitch to [Gomes] … I hate all that [garbage] that these things happen, but they have happened to us a lot lately.”

Duffy went six innings and gave up eight hits and six runs.

Lucas Duda hit a two-run home run for the Royals in the first, tying the score at 2. RBI hits by Whit Merrifield and Rosell Herrera, who had three hits for the night, put the Royals up 4-2 in the second.