Yankee Management Philosophy 101 (via Professor Carlos Beltran): “He’s a guy that’s signed here for seven years, so he’s the guy.”

Two nights ago, rookie Slade Heathcott inscribed himself into the 2015 season - and psychotic Yankee fan lore - with a climatic, game-winning home run.

And that's how people vanish from the New York Yankees...

FACT: Amelia Earhart, before disappearing in the Pacific, went 4 for 5 in a pickup softball game managed by Joe Girardi's grandmother.

FACT: Judge Crater, in his final appearance in pinstripes, threw six shutout innings for a team run by Brian Cashman's Aunt Louise.

FACT: Jimmy Hoffa, before going to bed somewhere below the Meadowlands' goal posts, homered to beat the Redsocks in 6-year-old Hal Steinbrenner's Strat-O-Matic League.

The Lindberg baby? Had just penned a Yankee contract. D.B. Cooper? Went 3-for-4 for Ralph Houk's beer league. The Lost Roanoke Colony? A new Yankee farm club. The crew and passengers of Malaysian Flight 370? You don't wanna know! (But it had something to do with A-Rod's cabana boy.)

So Heathcott - after delivering in the clutch - disappears into the void. Just as Rob Refsnyder did in July: Both rookies made one fundamental mistake: They homered to win a game. From there: Poof!

But wait: It's not just a rookie thing. On August 31, for one resounding moment in time, Stephen Drew started hitting. He went 4 for 4 against Atlanta. That's no misprint. Drew went four for four. So, next day... what happens? He sits. Yes, HE SITS! Of course, he does! He comes in as a late defensive replacement in an 8-3 loss to Boston. (He gets a meaningless hit, naturally.)

Last night, Yankee fans got to appreciate the flip-side of our franchise policy: Making sure the guy in a deep, soul-consuming slump stays put. I'm talking about the current pariah - Jacoby Ellsbury - who hasn't hit since Donald Trump declared, and who Joe Girardi refuses to bench, or rest, or drop in the order because - as Joe explains it, such a move would disrupt the fine-tuned Yankee clown car, as it clunks along the shoulder of the road. Nope. Joe will wait until Ellsbury goes 2 for 4 and then give him a night off.

So we take bets on which will happen first: Ellsbury will start hitting, or he'll tweak something.

Over the years, I've backed Joe Girardi. When the Yankees fail, I blame the boy owner. (I still scream as the thought of Yoan Moncada.) But this year - and I'm talking anecdotally - (which apparently is the formula by which we intend to elect the next President) - it seems as though Girardi has made bad decisions over and over. As The Donald would say: He's not having a good night.

Today's Times headline says, "Struggles At Plate Continue as Yankees Lose to Rays," and it's almost entirely about Ellsbury. The Daily News says, "Ellsbury Keeping Chin Up Despite Slump." Even the happy talkers in the YES booth spent last night chattering about whether Ellsbury should be out there. And the team keeps sliding. (Say, has anyone noticed how Michael Kay spends two hours each day whacking the Yankees on the radio, and then three hours each night, boosting them on YES. Poor guy is going to go nuts.)

This weekend, we have the Mets - who look ready to seal their hold on NYC by crushing us - and then we go to Toronto. Anybody who thinks the Yankees are a lock for the Wild Card - they're crazy. We have Ellsbury to watch. We have the Yankee motto: We signed him for seven, and we have five to go. Quick: Does anyone have a photograph of Slade Heathcott? We need it for the milk cartons.