In case there was any lingering doubt, the Yankees finally declared where they stand this season in loud and persuasive fashion Sunday morning by shipping Andrew Miller to the Indians for a package of four prospects headlined by Triple-A outfielder Clint Frazier.

The Miller trade comes six days after the Yankees sent Aroldis Chapman to the Cubs for three prospects, including the gem of the Chicago organization, Class A shortstop Gleyber Torres. Hal Steinbrenner, a reluctant seller, signed off on the Miller deal late Saturday night and Brian Cashman acknowledged Sunday morning that it was a difficult but necessary decision.

“This is a market that if you possess highly talented closers, as we had in our possession, you could exploit this market pretty strongly,” Cashman said during Sunday’s conference call. “We needed to have an extreme return.”

The Yankees also had to look in the mirror. In moving Miller, roughly 30 hours before Monday’s 4 p.m. nonwaiver trade deadline, Cashman made it clear they’ve switched into what can only be described as a rebuilding mode, something they haven’t done in almost three decades. Homegrown Dellin Betances, who went from seventh-inning guy to set-up man after the Chapman trade, will now take over as closer, with additional moves expected before the deadline.

Carlos Beltran, a free agent at season’s end, is likely to be traded. Ivan Nova, Nathan Eovaldi and Brian McCann also reportedly have been drawing serious interest from other teams. A few hours after Miller was shipped to Cleveland, the Yankees (52-52) were swept by the Rays, which torpedoed any posturing about not waving a white flag this week.

“We try to execute sound business decisions,” Cashman said. “That’s why this doesn’t feel different, because we’re just executing what we think is the best, sound decisions under the current circumstances. If we operate that way always, I think we’ll come out ahead most of the the time.

“Stay tuned. There’s a lot more time, a lot more things could happen. Could be additions, could be subtractions. And we are open to entertain all of it.”

The Yankees tried to patch the Miller hole Sunday by acquiring reliever Tyler Clippard (4.30 ERA) from the Diamondbacks for minor-league pitcher Vicente Campos. Cashman insisted the Clippard move — like getting Adam Warren in the Chapman deal — was proof that the Yankees, who are five games out of the second wild card, are not surrendering.

“Although the names don’t match up to the names we just lost,” Cashman said, “they are an effort on behalf of the organization and this front office to try to give our manager an opportunity to continue to fight.”

By trading a pair of elite closers, Cashman didn’t necessarily gut the roster. But having Steinbrenner greenlight those deals is evidence that the Yankees realize it’s time to restock at the lower levels. Cashman explained how the “chessboard” has dramatically changed since he first started under Hal’s dad in the late 1980s, and with so many more restrictions, it’s no longer as simple as outmuscling everyone with the Yankees’ checkbook.

“There’s just a recognition that, if you want to become a super-team, there’s certain ways to go about that, and that you have to strongly consider,” Cashman said. “The effort is always there dreaming and strategizing how to become that super-team that our fans can enjoy.”

Frazier, 21, was the Indians’ first-round pick (fifth overall) in the 2013 draft and Baseball America rated him at No. 21 on this season’s best-prospect list. This year, in 94 combined games between Double-A Akron and Triple-A Columbus (five games), the righty-hitting Frazier is batting .273 with 13 home runs, 48 RBIs, a .350 on-base percentage and .811 OPS.

“Frazier has an electric bat — his bat speed is already legendary,” Cashman said. “He’s got all the tools — he can run, he can hit, he can hit with power. He can play all three outfield positions. A very exciting, high-energy guy that shows up for the National Anthem in a dirty uniform.”

The Yankees received another first-rounder from the Indians in lefthander Justus Sheffield, 20, the 31st pick overall in the 2014 draft. Sheffield is 7-5 with a 3.59 ERA and 93 strikeouts in 95 1/3 innings over 19 starts at Class A Lynchburg this season. The Yankees also got a pair of hard-throwing righty relievers in Ben Heller and J.P. Feyereisen, with Cashman suggesting that Heller, the closer at Triple-A Columbus, could be called up to help the Yankees’ bullpen this season.