How much would it take for you to shave your beard?

The answer for this baseball player, apparently, was around US$324 million ($470 million).

The New York Yankees have coughed up the eye-watering amount to gain the services of ace pitcher Gerrit Cole on a nine-year deal from the Houston Astros.

However, thanks to a policy started in 1973 by former owner, the late George Steinbrenner, the oft-dishevelled-looking 29-year-old has had to present a more clean-cut image with his new club, removing his distinctive stubble and slicking back his once-wild mane of curly hair before donning the pinstripes for the first time.

Gerrit Cole shaved his beard to join the Yankees. ( AP: Mark Lennihan )

So why is this a thing?

The story goes that shortly after acquiring the team in 1973, Steinbrenner noted down the numbers of all the players whose hair fell below their collars after they removed their caps to sing the national anthem.

He handed the list to his player manager with the edict that those players needed to get a haircut, pronto.

That gave birth to the following policy:

"All players, coaches and male executives are forbidden to display any facial hair other than moustaches (except for religious reasons), and scalp hair may not be grown below the collar. Long sideburns and "mutton chops" are not specifically banned."

Incredibly, some players have been fined and benched for not adhering to this most unusual of policies.

In 1991, first baseman Don Mattingly was forced to sit out a game after failing to cut his mullet hairstyle — although he later did so, auctioning off the locks for charity.

In something of a coincidence, earlier that year the Simpsons parodied the Yankees hair policy in an episode that was aired after Mattingly had been benched — another example of the Simpsons predicting the future.

In the episode, Mr Burns repeatedly told Mattingly — who played himself as a ringer in the power plant's softball team — to remove his non-existent sideburns before eventually kicking him off the team.

Steinbrenner, who died in 2010, was a stickler for neatness — and his unusual policy is still strictly enforced by his two sons.

For his part, Cole — who is an admitted Yankees fan and even brought a banner he was pictured with as an 11-year-old at the 2001 World Series to prove it — fully bought into the policy.

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"He cleans up nice, doesn't he?" said Yankees manager Aaron Boone.

Cole, whose scruffy look dates back to his college days, was freshly shorn by the Yankees' barber on the morning of his press conference.

"I haven't shaved in like, 10 years," Cole said in the press conference after his unveiling.

"But, you know what, so be it, that's the way it is.