Aaron Boone wrote catcher Kyle Higashioka into the Game 4 ALDS lineup card Thursday night against the Rays instead of Gary Sanchez, and nobody should have been surprised.

That’s how far the former All-Star has fallen in the Yankees’ universe. It’s also what happens when a hitter who was feared for raw right-handed power checks in with a .147 (23-for-156) batting average during a short 60-game regular season and follows that by going 1-for-8 (.250) with a homer and three RBIs in two postseason games to go with four strikeouts.

Heading into the winter, the question that needs answering is does Sanchez remain a Yankee?

When Sanchez was crushing pitches over walls and driving in runs it made his defensive shortcomings easier to swallow. When he stopped hitting, those defensive flaws made it hard to write his name into the lineup in the most important games.

Boone said not using Sanchez to catch Jordan Montgomery in a must-win Game 4 on Thursday evening at Petco Park in San Diego had more to do with Higashioka’s solid work behind the plate and production from the bottom of the lineup.

It is easy to see why Boone paired Higashioka with Gerrit Cole down the stretch because Cole’s numbers were so much better throwing to Higashioka than they were to Sanchez. But using Higashioka with Masahiro Tanaka, who didn’t pitch well in a Game 3 loss, and Montgomery in Game 4 was a strong indication that Higashioka has passed Sanchez on the depth chart. And if the Yankees won Game 4 to advance to Friday night’s winner-take-all, there is no question Cole will start it and Higashioka will catch him.

Asked before Game 3 who his No. 1 catcher was, Boone said it was a day-to-day situation.

“Another close call for. Again, it comes down to Kyle earning these opportunities. I feel he is providing enough offensively and doing a great job behind the plate,’’ Boone said of his Game 4 choice. “Honestly, I felt I could have gone with Gary as well and felt good about that. In the end, after contemplating and talking with some coaches a little bit this is the way I felt I wanted to go.’’

If the Yankees escape the 2-1 ditch they were in Thursday night and reach the World Series, Boone won’t use Higashioka to catch every game, especially if it goes seven games.

However, starting one of two games in the AL Wild Card Series — in which he homered in the clinching victory — and one of the first four ALDS tilts clouds Sanchez’s future with the Yankees.

GM Brian Cashman has been very supportive of Sanchez throughout his defensive struggles and reminding people he is the regular catcher. But at what cost? Sanchez made a prorated $5 million this year and has two years of arbitration remaining. If he gets a small bump in arbitration, is a .147 hitter with serious defensive flaws worth that? Based on this season, Sanchez’s trade value has plummeted so he fits into the classic “that would be selling low’’ situation.

Yet, there is no guarantee the Yankees will ever be in position to sell high on Sanchez.

Higashioka isn’t likely to morph into a front-line catcher at age 30 whose strength is defense. J.T. Realmuto, easily the best catcher when free agency opens, might be out of the Yankees’ price range after they dropped $324 million on Gerrit Cole last winter and need to bring batting title winner DJ LeMahieu back. That will require much more than the two-year deal for $24 million they signed the second baseman for prior to the 2019 season.

Sanchez hasn’t reached the bottom Jesus Montero did. However, he isn’t close to the two-time All Star who hit 85 homers and drove in 220 runs from 2017-19.

So what is Sanchez? Only the biggest decision of the Yankees’ offseason.