NEW YORK — It didn't make the back page of the Thursday's New York tabloids, so the controversy seems to be limited to just the Yankees broadcast and Bronx Bombers fans ... for now.

As Yusei Kikuchi dominated the Yankees over the first five innings on Thursday night, holding them hitless in an eventual 10-1 win, the YES Network cameras began to focus on his navy cap, specifically bottom part of the left side of the bill. Because Kikuchi has a pronounced bend in the bill, unlike most current major-league players, it was easily visible.

There appeared to be a substance in that area that the broadcast believed was pine tar that Kikuchi was using to his extreme benefit. Throw in the fact that Kikuchi has an almost obsessive compulsive habit of tugging on that part of his cap, two and three times in between pitches, and it fueled the conspiracy.

That video and screen grabs from the broadcast soon made the rounds to Twitter and other social media platforms, even prompting a well-served fan in front of the press box to spend the better part of a half-inning screaming at home plate umpire Angel Hernandez to check Kikuchi's hat and that he was cheating.

Nobody from the Yankees asked Hernandez to check Kikuchi's hat.

"I was aware of it very late," manager Aaron Boone told reporters postgame. "I heard they were talking about it. I was made aware of it sometime in the eighth inning there. So I'll take a look at it, and we'll kind of see what we make of it."

Yankees hitters had no outrage.

"I could care less," Cameron Maybin told reporters. "Nobody noticed it. Nobody said anything. We've got a lot bigger worries trying to manufacture runs and get guys on base. I don't think that had anything to do with it."

Asked about it before Thursday's game, manager Scott Servais deadpanned: "I have no idea what you are talking about," before breaking into a cackle at his own joke.

"I think it will all work itself out," Servais said.

So what was on Kikuchi's hat?

The Mariners won't publicly say that there was anything on the bill other than sweat and rosin from the legal rosin bag on the mound.

Realistically, there was probably pine tar or some sticky substance that improves grip which was accentuated and made noticeable by a large amount of sweat and rosin.

Here's a note about Kikuchi: He sweats ... a lot. The instant sports recall are basketball players like Patrick Ewing and Kevin Garnett dripping sweat during games or Cristiano Ronaldo in soccer. Auburn men's basketball coach Bruce Pearl will blow through a suit in a game. Former Mariner prospect Clint Nageotte was notorious for sweating with droplets coming off the bill of his cap as did Freddy Garcia.

In one game, Kikuchi will go through three game jerseys and have to have his calves massaged because of cramping. It should be interesting when he has to pitch in Texas in July and August.

The perspiration, particularly on the forearm, wrist and hand, is alleviated with the white, sandy rosin. Once Kikuchi touches anything, the rosin will be noticeable. It will also stay noticeable if there is an additional substance on the material.

If Kikuchi has pine tar on his hat, he is technically breaking the MLB rules. Per Rule 6.02 C (4) of the official rule book, a pitcher may not "apply a foreign substance of any kind to the ball."

But he wouldn't be the only one in violation. The use of pine tar or bullfrog sunscreen mixed with rosin, aerosol stickum or other substances to improve grip are commonplace in baseball. Check the back of pitchers hats, the top of their bills, the side of their glove, you'll see discoloration from some substance, plus sweat and rosin.

"I'd say 99 percent of pitchers are using something," Haniger said. "It's on their hats, it's on the strings of their gloves or their belts. They'll have it on the palm of their glove hand and use it to rub up the baseball and you see them really push it against their hand."

Haniger admitted he uses some when he's in the outfield because the new baseball from Major League Baseball is so slick that "it's like picking up a cue ball."

MLB has stopped allowing teams to rub up baseballs with mud before games, which has made it even worse.

"I don't mind if they are using it for grip, but if you are using to increase your spin rate on your fastball or break on your slider, then I do," Haniger said. "But I don't know how you'll be able to distinguish those."

The most notable incident of pine tar use was Michael Pineda getting ejected from a game on April 23, 2014 while pitching for the Yankees at Yankee Stadium for having a noticeable smear of pine tar on his neck.

To be fair, most pitchers try to be a little more inconspicuous than Pineda.

More recently, Indians pitcher Trevor Bauer accused Astros pitchers of using foreign substances to increase spin rate.

Thanks to the magic of Baseball Savant, a website that works in conjunction with MLB, the spin rate data for Kikuchi was available. The spin rate on his fastball, curveball and slider vs. the Yankees were all slightly lower than his previous outing in Cleveland. His spin rates all registered within a normal margin.

Servais wasn't certain whether the Yankees would make it an issue in the final game of the series or if the A's will make a big deal about it in Kikuchi's next scheduled start. But logic says that if an opposing manager asks to check Kikuchi for pine tar, the Mariners would immediately return serve and have an opposing pitcher who they knew was using pine to get checked by the umpires.

That back and forth is a reason why teams don't usually get involved in the scenario. They know their guys use it too. The players and teams all know that it's out there and most of them simply don't care.