“I remember watching Leafs games, watching Darcy Tucker flying around with his ‘bucket’ off in warmups. I thought it was so cool,” O’Reilly recalled recently.

Tucker spent most of the first decade of the 2000s playing for the Toronto Maple Leafs, and as the saying goes, he had some flow.

Although eight years younger than O’Reilly, at age 23, Robert Thomas feels the same way.

“Growing up, you watch guys going out in warmups without a helmet on,” he said. “I always thought it was pretty cool growing up and I wanted to do it. There was a lot more back then. I felt like most guys did it.”

But there are less and less going helmetless these days, and after the next decade or so there will be none. That’s because the NHL quietly instituted a rule in mid-November making the wearing of helmets mandatory during pregame warmups as a safety measure for all players who entered the league after 2019-20.

Similar to the mandatory visor rule that was instituted for the 2013-14 season, it’s grand-fathered in. The visor rule applied only to players with less than 25 games in the NHL.

As players retired and new players entered the league, the number of visor-less players dropped every year. Today, only about a dozen remain without wearing visors — one of whom is O’Reilly, who entered the league in 2009.

Predictably, he’s not fond of the new pregame mandate for helmets.

“No, I don’t like it,” O’Reilly said. “It’s what we’ve been doing for years. I don’t know, I think it’s kind of an old-school thing. I didn’t think they needed to (change the rule), but it is what it is.”

Several Blues interviewed in the days and weeks leading up to the All-Star Game/bye week break felt the same way. They don’t like the new rule, but it’s not like they’re losing any sleep over it, either.

“I think it’s a way for fans to kind of see players and their faces a little bit,” defenseman Justin Faulk said. “I know at some point it was voted on, approved by whoever needs to vote on it. I don’t know. I don’t see the point to have a full rule on it.”

Faulk, Thomas and O’Reilly are among about a half-dozen Blues who go helmetless. The group of helmetless regulars here also includes Torey Krug and Robert Bortuzzo.

O’Reilly actually is kind of a half-and-half guy. During any particularly pregame, he can be seen wearing his helmet for part of it, and not wearing a helmet for part of it.

“Once I start skating fast — I don’t really trust my skating — so that’s when I put my helmet on,” O’Reilly said, laughing. “Halfway through warmups I put it on.”

There have been other, let’s call them special occasions, when various Blues have gone helmetless.

Circle back to the Blues’ 2019 Stanley Cup run, and Brayden Schenn went helmetless during warmups before Game 5 of the team’s opening-round playoff series against Winnipeg. He had gone pointless in the first four games of the series and explained at the time: “Sometimes you just gotta change ’er up.”

In Game 5, after going helmetless pregame, he snapped out of his slump with a goal and an assist in a 3-2 Blues victory. Not that he was superstitious or anything, but Schenn then went helmetless for the next several pregames.

And then there was the Blues’ March 2 game last season at Madison Square Garden against the New York Rangers. It was Pavel Buchnevich’s first game against his old team, and he came up with the idea of the entire team coming out for pregame warmups helmetless.

(He denies it was his idea, but too many Blues claim otherwise.)

“We thought we’d all kind of go along with him and do it,” O’Reilly said.

It was quite a sight, 18 skaters with hair flowing in the breeze as they skated during warmup. All with some hair product helping to keep things from getting too out of place.

“We have actually a couple barbers that are in there (the locker room) making sure that we’re styled up,” O’Reilly said.

He was just kidding here. About the barbers. Not about the use of hair gel, etc.

“I’ve always got a lot on,” O’Reilly said. “I’ve got pretty curly hair in general; that (hair product) usually holds it in place pretty good.”

For Thomas, the use of hair-styling products is a game day decision depending on whether he’s having a bad hair day.

“Exactly,” he said. “You never know.”

But it’s clear one of the NHL’s quaint traditions is being phased out, with spinoff effects in related areas. Such as the tradition of players taking a lap by themselves to start pregame activities, without helmet, before their first NHL game.

When Springfield call-up Will Bitten played his first NHL game, Dec. 3 in Pittsburgh, he came out wearing his helmet because the new rule already was in effect.

The list of players getting injured during pregame warmup is an extremely short one, further fueling the notion that this new rule is unnecessary.

O’Reilly was asked if he was ever struck by a puck in practice.

“Knock on wood here, I don’t think I have,” he said. “Not in the head with a puck or anything like that. I think I was high-sticked once just by accident.”

Of course, there was a notable exception in 2012, when Corey Potter stepped on the face of Edmonton teammate Taylor Hall, who had fallen along the boards during warmup. Hall needed 30 stitches to close a gash above his left eye.

Thomas, like most of his currently helmetless teammates, gets the safety aspect of it — at least to a degree. But he wishes there could be exceptions, such as for a player making his NHL debut.

“It’s hard to tell who a lot of people are with the helmet on,” Thomas said. “You don’t know who’s underneath it, so it’s a good way to show.”

Faulk says it’s an unwritten rule that young players can’t go without a helmet in warmups anyway.

“You have to earn it,” he said. “You don’t get to do it Day One. You gotta spend a few years in the league before you get to pull your helmet off, I think.”

Back when he was a young player for Carolina, Faulk said he checked with veterans to make sure it was OK. But those days are gone.