The Yankees’ Summer Siesta and the Red Sox’s historic roll have intersected to create a Bronx biosphere of sorts, where the hometown team can experiment with few consequences.

Their next experiment should place Justus Sheffield on the Yankee Stadium mound on Friday night and see how he responds.

Before the Yankees and Mets concluded the 2018 Subway Series at the Stadium, the Yankees made some news by placing their spiritual leader CC Sabathia on the 10-day disabled list with right knee inflammation.

“I think it’s as expected,” Brian Cashman said, explaining that Sabathia figured to take some down time to rest his surgically repaired knee, and the Yankees’ general manager expressed his hope that the big lefty would miss only one start, a possibility since the Yankees don’t play on Aug. 20 or Aug. 23.

To substitute for Sabathia on Friday against the Blue Jays at home, the Yankees could let Sonny Gray, recently demoted to the bullpen, get another shot. They could turn to rookie Chance Adams, who handled himself well in his major-league debut on Aug. 4 against the Red Sox at Fenway Park. Or they could call upon Luis Cessa, currently Adams’ teammate at Triple-A Scranton/Wilkes-Barre, who didn’t embarrass himself in three Yankees starts earlier this season.

All of those choices would be perfectly acceptable. Yet why not capitalize on this feast of cupcake opponents and make a move with greater potential long-term gains?

Sheffield, the 22-year-old left-hander, has pitched to a 2.19 ERA in 20 minor-league appearances, 19 of them starts, this season. He has struck out 114 and walked 45 in 107 innings, a good yet not great ratio. He has lasted five innings or more in each of his last 11 starts.

Sounds like a man who has earned a cup of coffee, doesn’t it? If he gets bombed, he can chalk it up as a learning experience, and the Yankees can shrug it off and get back to work amidst this 27-game stretch, of which Monday night marked number eight, that includes three games against the mediocre Rays (who arrive at the Stadium Tuesday) and 24 versus awful clubs. Every game counts? Eh. The Red Sox stand hopelessly ahead of the Yankees, more likely to set a record for wins in a season than to finish in second place, and the Yankees in turn own a comfortable advantage over the A’s and Mariners for the top wild-card seed.

The one obvious drawback to this plan is that Sheffield doesn’t currently occupy a spot on the Yankees’ 40-man roster, which Cashman has established as one of the industry’s deepest. However, that doesn’t constitute reason enough to spike this plan. Clint Frazier, still battling his scary concussion issue, could go on the 60-day disabled list, as could pitcher Domingo Acevedo, who is currently inactive.

Sabathia pitched brilliantly against the Rangers on Sunday, allowing only Joey Gallo’s swinging-bunt single over six innings, although he did seem bothered by his knee at times. He has appeared on board, in general, with the Yankees’ conservative approach to his usage, even though he has bonus clauses in his contract for reaching certain innings-pitched totals, starting with 15 (which would still be attainable with a quick return).

“He’s a pro,” Cashman said of Sabathia. “He knows that whenever he has to, [to] raise his hand to say, ‘It’s best for the next turn for me to skip it, take the time out so I can get back up and running.’ We’re adjusting to his feedback.”

Now the Yankees can adjust to The Post’s feedback: Give Sheffield a chance. Turn Sabathia’s little break into a big break for the highly touted pitching prospect.