Gary Sanchez ’s slump hasn’t let up. He finished the homestand with a hitless afternoon and has just 10 hits in his past 75 at-bats. In that 19-game stretch, Sanchez has three extra-base hits and six walks, while striking out 26 times.

“I don’t feel he’s far off,” Boone said Sunday as the Yankees lost to the Rockies, 8-4. “He’s expanding the strike zone a little bit more than usual. But he’s getting his ‘A’ swing off a lot.”

And the manager remains confident that when Sanchez does break out, it won’t take him long to be productive.

“A hitter like him has got to keep grinding away, because it’ll turn and some people will pay a big price,’’ Boone said.

Sanchez’s tough day at the plate wasn’t helped by the oppressive heat. His passed ball with the bases loaded in the eighth cost the Yankees a run, although it was a tough call, as Stephen Tarpley missed his spot with the pitch.

Since the Yankees decided to not option Tarpley back to the minors after he tossed three innings out of the bullpen on Friday, they were left without a clear-cut long man out of the bullpen on Sunday, so Adam Ottavino came in to pitch an inning despite the Yankees trailing by six runs at the time. It was his third appearance in four days.

“We were just kind of up against it,’’ Boone said. “We had to piece it together … and we needed a few batters [from him] there.’’

Aroldis Chapman, who hadn’t pitched since Monday, tossed a scoreless ninth.

The Yankees put the same heat advisories they used Saturday in place on Sunday, since it was just as hot at the Stadium. Extra hydration stations were located throughout the park. … CC Sabathia turned 39 Sunday, and will start against Minnesota on Monday.

— Additional reporting by Greg Joyce