It’s no easy decision to leave college hockey for the pros. Just ask Bruins star Charlie McAvoy.

Charlie McAvoy is in his sixth NHL season.Michael Dwyer/Associated Press

Charlie McAvoy was sobbing. He was letting it all out.

He might have made the wrong decision. Or the right one. He didn’t know. He was 19.

The weight of his choice — he had signed an amateur tryout agreement with the Bruins, leaving Boston University for good — was smacking him in the face.

“I remember how final it was,” McAvoy said, sitting at his stall in the Bruins’ dressing room at Warrior Ice Arena following Tuesday’s morning skate. “As soon as the pen touches the paper, that’s it.”

Six years ago Wednesday, and four days after the Terriers were eliminated in the NCAA West Regional final in Fargo, N.D., McAvoy departed his dorm at BU for the last time. He stopped by Bruins general manager Don Sweeney’s office, a few streets away in Brighton. Members of the equipment staff handed him his Providence gear and former travel coordinator Whitney Delorey gave him his paperwork.

McAvoy and his now-fiancee, Kiley Sullivan, made a heavy-hearted drive from Brighton to Providence. They laugh about it now, but there wasn’t much she could tell him, he recalled, as he was “crying like a baby” on the hour-long trip.

“There weren’t many assurances,” McAvoy said. “I was betting on myself to go down there and play well, and get a chance the following year.”

The defenseman’s stay wasn’t long at the Regency hotel in Providence, where he was essentially in another dorm, with Dan Vladar and another new signee, Ryan Fitzgerald. McAvoy played more games of NBA 2K on XBox (with Malcolm Subban, Rob O’Gara, and Jake DeBrusk) than he did games for the Providence Bruins (four).

His two-week stint in the minors ended when Torey Krug and Brandon Carlo were hurt. From the day he was called up for practice, on April 10, McAvoy shattered the learning curve. He made a seamless NHL debut in Game 1 of the first round of the playoffs against the Senators. He logged 24:11 and was on the ice when Brad Marchand scored the winning goal with 2:33 remaining.

“I remember not knowing if it was the right decision,” he said. “Obviously, it was. It was unfortunate with guys getting hurt. It was crazy. I remember that day, the pit in my stomach, was I doing the right thing?

“My conviction wasn’t 1,000 percent. I was obviously more than 50, so that’s why I did it. Quinny [then-BU coach David Quinn] gave me a lot of confidence. He was like, ‘You’re ready, it’s your time to go.’ He was kind of the deciding factor, him believing in me and knowing I can do it.”

Another college sophomore is in McAvoy’s shoes. Ohio State’s season is over, and 22-year-old Mason Lohrei, the Bruins’ best defensive prospect, could sign an amateur tryout agreement this week. Like McAvoy in 2017, Lohrei is a top player on a tight-knit college team who has shown his readiness for the pros. His call will be just as tough.

In two seasons at Ohio State, Mason Lohrei had 61 points.Greg Cooper/Associated Press

The Bruins are as stacked as any NHL team in recent memory. There are NHL-caliber defensemen in Providence. The college experience is priceless.

McAvoy, like those around him six years ago, couldn’t offer Lohrei much advice.

“It’s a tough one,” McAvoy said. “When I came in, I felt there was room for me to poke my head in and see if I could stick around. Obviously we’ve had a crazy year, with a lot of established guys. In that regard, I’m not really sure what that looks like. Maybe it means he has more time than he thinks to make a decision.

“I did it, and I had times I wished I didn’t do it, and it was a little hurdle there for a month. Then all of a sudden, I’m playing in the NHL.”

Montgomery plugs in Pastrnak

Over the last two months, the Bruins are sleepwalking through an 11-for-93 funk (11.8 percent) on the power play. They believe passion, rather than personnel, is the issue.

Before Tuesday’s 0-for-5 performance in a 2-1 loss to the Predators at TD Garden, coach Jim Montgomery committed to using David Pastrnak at the start of, and for long stretches of, every power play. He could be on the ice with the first unit (Patrice Bergeron, Marchand and Co.) or the second unit with Czech mates David Krejci and Pavel Zacha.

Pastrnak logged a game-high 7:16 on the power play Tuesday night against Nashville.Michael Dwyer/Associated Press

Unless, Montgomery added, Pastrnak is “really exhausted.” But “he seems to get pretty energized, though, when the ref goes like this,” Montgomery said, raising his arm as if signaling a delayed penalty.

Pastrnak, who scored his 52nd goal with under a second left in the loss, logged a game-high 7:16 on the power play and landed zero shots on goal. Zacha had two of the Bruins’ five PP shots.

Around the rink

Linus Ullmark (21 saves) dropped to 36-6-1 but improved his goals against average (1.90) and save percentage (.937). If Montgomery continues his goalie rotation, Ullmark could have four more starts to equal Tim Thomas’s club-record .938 save percentage from 2010-11 … Bergeron, Marchand, and Hampus Lindholm returned after resting Sunday with what Montgomery called “nagging injuries” … Jakub Lauko, who sustained an upper-body injury Sunday, did not practice. “It’s day to day,” Montgomery said. “It’s nothing a 23-year-old won’t get over in due time.” Lauko turned 23 Tuesday … Nick Foligno (knee) participated in practice for the first time since his Feb. 28 collision with Nikita Zadorov in Calgary. Taylor Hall (knee) was also present. Neither is expected to play before the postseason. Montgomery said a report from TSN that Hall is ready but being held out for salary cap reasons was “false” … Oskar Steen remains up from AHL Providence on emergency recall, but was scratched … If the Bruins beat the Blue Jackets Thursday, they would be in a tie as the fourth-fastest club to capture the Presidents’ Trophy (75 games), with the 2015-16 Capitals and 1985-86 Oilers. The 1995-96 Red Wings did it in a record 71 games, the 2018-19 Lightning in 73, and the 2001-02 Red Wings in 74 … The Bruins made a $10,000 donation to the Nashville Predators Foundation, held a moment of silence before the game, and wore helmet stickers honoring the victims of Monday’s school shooting in Nashville. Montgomery opened his pregame press conference by expressing the Bruins’ “deepest sympathies to the families and friends affected by the unfortunate shooting — again.”