HOUSTON — Aaron Boone conceded games during the season, allowed a few nightmarish blowouts against his bullpen’s soft underbelly, all in the philosophy of lose the battle, win the World.

He knew from George M. Steinbrenner Field on that he had a playoff team. So Boone embraced the big picture. The Yankees manager protected his relievers, never asked any to pitch three straight days, making the Yankees the only team during the regular season in that column.

Boone turned September into a spa month for the best of his pen, so light was their workload. All the preservation was done with October in mind. The Yankees saw those special relievers as the strength of the team; input those pieces into playoff games early and often and ride that to the Canyon of Heroes.

That strategy did not work. Dellin Betances (Achilles) and Domingo German (administrative leave after allegations of domestic abuse) were not available, shortening Boone’s reliever of trust group. Adam Ottavino pitched himself out of that ring. So the Yanks were down to four for Saturday’s game and three — Chad Green, Tommy Kahnle and finally Aroldis Chapman — yielded all the runs in a 6-4 loss.

The Yankees dreamed for months of funneling the ball to Chapman in a huge October moment. And even with the failure of Green and Kahnle and more hitting travails in the clutch, the Yanks were in a 4-4 tie after DJ LeMahieu hit a two-run homer with one out in the ninth. That was in a 10-pitch battle against Houston closer Roberto Osuna. The Yanks had struck a blow to get to Game 7, to get another shot at Gerrit Cole. They just needed Chapman to get them to extra innings.

But Chapman walked George Springer with two out and hung a slider that Jose Altuve crushed to send the Yanks into the offseason. Chapman paused for a few seconds and stared in the direction of where the ball had crashed above the Crawford Boxes in left.

“I just couldn’t believe it,” he said.

It was real. The Yanks just may have been the second-best team in the majors each of the past three seasons, being eliminated by the eventual champs in 2017 (Astros) and ’18 (Red Sox), now again by Houston. The Astros were the better team — don’t ignore the superiority on defense and on the bases. The Yankees’ best chance to negate the Astros’ edges was with their bullpen. But they lost Game 2 and a chance to take a stranglehold with two wins in Houston, largely because Ottavino allowed Springer the tying homer on his first pitch in the fifth inning.

And they lost their final game as Green, Kahnle and Chapman failed to do what remarkably J.A. Happ and Luis Cessa could — shut down the Astros.

“It’s frustrating because the team was built to get the ball to the back end and we got it there and we didn’t get the job done,” Zack Britton said. “That was the message all year [get it to the big relievers].”

In Game 6 Boone could have tabbed a traditional starter in Happ. Instead, he went with the perceived strength, hoping Green could douse the Astros’ righty might from the outset. But Green, even when getting outs this postseason, had been hit hard often. And among the problems with using pen guys so much in a series is showing them to hitters a lot. Relievers are generally relievers because they have one excellent pitch, perhaps a second.

Seen once in a while that is a weapon. See it frequently and overexposure sets in — both Britton and Kahnle noted how well Houston had adjusted with frequent looks. When Yuli Gurriel batted with two on and two out in the first, he was taking his fourth at-bat of this ALCS against Green. Gurriel was just 1-for-20 in the series, but two of his outs were liners against Green. Gary Sanchez went to the mound to talk to Green, Happ warmed. Green tried to beat Gurriel with a first-pitch fastball up. Gurriel opened up and crushed it into the Crawford Boxes.

It was 3-0. Houston had won its previous 65 home games when it constructed a three-run lead — last losing in July 2018. They would win here, too. Kahnle, as the first Yankees reliever to work three straight days, surrendered a sixth-inning run. And after LeMahieu’s dramatics, Chapman could not save the season.

“We always feel good when we get our bullpen in the game,” Britton said.

The plan had been incubating since February, hardened over the months of the season. Preserve the bullpen arms. Have them primed for October. Get them into the game over and over.

In the end — for the Yankees — that strategy did not provide relief.