With piercing eyes and a scalp shorn to the skin, there is an unassuming ninja on the prowl at 161st Street. Teammates proceed with caution in his company; drop your guard, and you can easily become his next victim. “You better keep your head on a swivel,” he warns, and they would be best to abide.

Brett Gardner may be 36, married with two boys and a big leaguer of 12 seasons, but he still pulls off pranks with the same elation that a child would display. It’s evident in the sly grin on his face when asked about the shenanigans, in the devilish laugh that precedes his answers. A simple man by his own admission, Gardner gets a kick out of messing with his teammates during baseball’s marathon season.

Just ask Aaron Judge, who, during his rookie campaign in 2017, was tricked into taking a group photo after Gardner had lined the inside of his helmet with eye black. When asked to remove his helmet for the snapshot, Judge’s forehead was slathered in the greasy black polish. “I had to wear that one,” Judge says, quite literally. “Thankfully that picture hasn’t gotten out yet.”

Then there’s Clint Frazier, who couldn’t for the life of him understand why the Yankees’ clubhouse chef had concocted an unbearably spicy take on penne alla vodka earlier this season. The cook, however, had no idea why Frazier’s taste buds were suddenly set ablaze. But Gardner knew; he had mixed “an absurd amount” of crushed red pepper into the pasta when Frazier wasn’t looking.

The young outfielder had forgotten for a moment the risk that comes with taking his eyes off his plate when Gardner is lurking. Yankees who have been around longer know better, though. “Anytime any little thing is wrong with something in the clubhouse,” CC Sabathia says, “everybody automatically looks at Gardy.”

Gardner’s tricks can take on a spoken form, as well. Frazier describes him as a “professional trash-talker,” the kind of guy who will convince you you’re wrong when you know you’re right. “You can’t beat that guy in an argument,” Frazier yields, ceding the field to his gaslighting elder. “He’s just a competitor at all times.”

Austin Romine stays mindful of his phrasing around the sneaky, articulate speedster, as conversations with Gardner often become verbal traps. “You’ve got to try and stay a step ahead because his brain processes not only the game, but life, in a very quick way.”

Gardner relishes his reputation for stirring the pot. “Just keeping guys honest,” he says with a sly giggle. He declines to share any stories himself -- he’s not exactly his own favorite talking point -- but Gardner’s teammates make it clear that there are plenty more to be told.

It’s all in good fun, though. “I think he’s hilarious,” Frazier says. As one of the veteran leaders in the Yankees clubhouse, Gardner is just trying to lighten the mood -- even if that occasionally means being a pest.

Most of the Yankees are on to him by now. They know that it would be foolish not to pay attention to Gardner. Yet, even after all these years, he still manages to surprise.

***

With all the injuries that the Yankees dealt with in 2019, Gardner probably saw more playing time than he expected to. And when he wasn’t on the field? Gardner was more visible than ever in that regard, as well.

Minus a short trip to the 10-day IL with left knee inflammation, Gardner was a constant for the frequently hampered Yankees this season, yet simultaneously a bit unlike the guy the baseball world had gotten to know since his debut in 2008. At least that’s how it seemed from the outside looking in at the viral videos of Gardner acting demonstratively during games.

The former college walk-on has always been the spark plug sort, but there were times this season when Gardner appeared even more animated and fiery than in years past. His bat-banging theatrics -- which dented multiple dugout roofs, including the Yankees’ own -- and run-ins with umpires could have left fans wondering if a midlife crisis was unfolding before their eyes. But there were other instances in which the vivacious, enthusiastic personality that the Yankees know and love behind the scenes was on display for all to see.

Giddiness took over on Sept. 1 when Mike Ford hit a walk-off home run to beat the A’s. While the ever-ebullient Tommy Kahnle was running chaotic victory laps in the bullpen, a smiling Gardner waddled from the dugout carrying a Gatorade cooler. He promptly used it to bathe Ford after the rookie followed up Gardner’s game-tying homer with a dinger of his own to send the Yankees to their 90th victory.

There was also the helmet incident in Cleveland in early June, the one that resulted in a bloody lip after an irate Gardner, slumping at the time, threw his protective headwear at the helmet rack out of frustration, only for it to ricochet back at his face. Romine watched the outburst unfold before doing his best impression of the That’s None of My Business meme.

So, what got into Brett Gardner in 2019? Romine says he’s just a passionate player playing with … well, passion. Judge chalked it up to an increased number of microphones and cameras infiltrating stadiums, which have given fans a better idea of what transpires down on the field and in the dugout. And then there’s Sabathia, who insists there was nothing new going on with his longtime friend.

“He’s always been the same,” the veteran pitcher says. “Maybe you guys are paying attention more, but that’s always been Gardy. He’s always been the life of everything in here. In the dugout, he’s always the one yelling, screaming, hollering. People never paid attention, but now they are.”

Maybe it’s that simple. Maybe it was possible to overlook the steady and dependable outfielder whose career bridged the gap between the Core Four and the Baby Bombers.

Now, it seems, the vibrant character known for wreaking havoc behind the closed doors of the Yankees clubhouse has shed his cloak of mystery, fully introducing himself to more than just teammates. With roughly 1,500 games under his belt and another contract year coming to an end, Gardner has made it a point to live it up a little more.

“I’m just trying to enjoy myself, really,” he says. “We just have a fun group of guys, and it’s been a really good year for us -- aside from the injuries -- up to this point on the field.

“The older you get, maybe the smarter you are. You learn to appreciate things a little more.”

***

Gardner won’t play for the Yankees forever. On one hand, that’s obvious. No one plays anywhere forever. And yet, after more than a decade in pinstripes, it’s hard to imagine the Yankees without Gardner.

Stranger still is picturing him in another uniform. After all, he is New York’s longest-tenured player. But he’s also the Yankees’ second-oldest position player, and baseball -- more than ever -- is a young man’s game, and the Yankees have some considerable outfield talent coming up through the ranks. Eventually, there will come a day that will be Gardner’s last in pinstripes. There’s a chance that day could come this October.

As much as he wants to stay in the moment, Gardner divulges that his mind will occasionally wander toward the future. That admission is as far as his comments will go, though. He’s slated to hit free agency for the second consecutive offseason, but when asked what he personally hopes his future holds, he talks about winning the division, securing home-field advantage, marching through the postseason and delivering another championship to the city of New York. “Past that, I’m not really worried about what’s going to happen,” he says.

He doesn’t have to come out and say he wants to remain with the Yankees, but, reflecting on last offseason, he notes that he never got to the point of considering other clubs. Even after Gardner’s option was declined, Yankees general manager Brian Cashman and the front office quickly made it clear that they wanted him back. He was on the same page.

“I never really wanted to go anywhere else,” Gardner says. “It was an option, but my first option was, obviously, I wanted to come back here. I’m thankful it worked out the way that it has.”

So are the Yankees. With outfielders Judge, Aaron Hicks, Giancarlo Stanton and Cameron Maybin all spending swaths of time on the IL, Gardner seized the opportunity to play more than anyone could have expected last Halloween when the team announced he’d be coming back. The South Carolina native set career highs in home runs and RBI in 2019, and, as of mid-September, only Gleyber Torres and DJ LeMahieu had appeared in more games.

But Gardner’s value exceeds his contributions on the field. It’s no secret, with adjacent lockers that provide a front-facing view of the entire clubhouse, that he and Sabathia have been the de facto captains in the post-Jeter age. While Sabathia’s exit has been decided — he will retire when the Yankees’ season comes to an end — Gardner’s next steps are yet to be determined.

There’s a chance two prime pieces of clubhouse real estate will open up in 2020, as well as the symbolic positions that the current tenants occupy. But both Gardner and Sabathia take pride in the fact that they have been partly responsible for passing on the same messages that the Core Four once preached to them. With so many young Yankees following their lead, this is as much a part of their legacies as any World Series ring or accolade.

It takes some nudging after an initial question about his leadership — “That’s not something I’m really comfortable talking about,” Gardner says — but he ultimately relents. Once the novice on a predominantly veteran roster, he understands his impact in the room. There’s a reason why Judge calls him “one of the best teammates, if not the best teammate, I’ve ever played with,” and why Frazier thinks of him as “such a force in this clubhouse.”

But then Gardner deflects and recognizes Sabathia’s influence. He notes that Judge is mature beyond his years, as is Torres, Gary Sánchez and other youngsters. He praises fellow veterans, such as Hicks, LeMahieu, Stanton and Maybin, for stepping up after previously playing for other teams. It doesn’t take long for Gardner to identify half the roster as leaders. Again, this was supposed to be the answer to a question about himself.

Gardner’s making a point, though.

“If and when the time comes for me to be gone,” he says, “they’ve got a great core in place.”

Gardner’s certainly right. But there’s also no denying that the fleet-footed, trash-talking, practical-joking, intense teammate for all these years has something to do with that. Regardless of when the end comes, Gardner’s mark has already been made in the Bronx.

“Day in and day out, he’s working hard and he’s motivating not only himself, but guys around him. He challenges us, and you can see it in his play,” Judge says. “He’s a leader, a guy that you need here in this clubhouse. That’s why he has been around so long.”