BOSTON — If Boston University coach David Quinn had any trace of doubt about how special prized recruit Jack Eichel was going to be for the Terriers, the freshman eliminated it early in the third period of his collegiate debut at Massachusetts.

BU opened the period with a slim 2-1 lead and a penalty to kill. After that man disadvantage, the Terriers returned to full strength — and then some.

At 1:54, Eichel took a pass from Brandon Fortunato just outside the blue line, took three or four big, easy strides and fired a wrist shot between two defenders that cleanly beat the UMass goalie, stick side. Then, less than a minute later, Eichel got the puck at the top of the left-wing circle. Moving the puck to his backhand, he evaded one defender, skated toward the net and slipped a backhand pass right between the legs of another Minutemen player, perfectly teeing up Danny O’Regan for the first of many times this season.

In just 44 seconds, it was game, set, match for the Terriers, who exploded with four more third-period goals to rout UMass 8-1.

“In 40 seconds, he changed the whole complexion of the game,” Quinn says now. “Sets up a goal, scores an unbelievable goal, and it’s 4-1. In essence, the game is over. That’s when I knew. Because the first two periods there wasn’t too much happening for him. That was his first real wow moment. … I think guys were like, ‘Whoa.’ You just could sense it because it happened so fast. It kind of set the tone for the year.”

Indeed, that was just the first of a veritable highlight reel of a freshman season in which he has surged to the top of the NCAA scoring chart and helped the Terriers regain a place in the forefront of the national picture.

On Nov. 21, there was the end-to-end rush in overtime, when Eichel spotted Maine changing lines and turned it up a gear to race up the ice and score. Then there was the night in December that he set up all four of BU’s goals, including a blind backhand pass from the corner that found O’Regan’s tape for another gem.

But a defining moment was his game winner against UMass-Lowell on Jan. 18. BU needed a win to tie the River Hawks for first in the Hockey East standings, and the game went into overtime. At 1:09, Eichel was boarded hard into the River Hawks bench by Evan Campbell. On the resulting power play, Eichel looked like a guy who couldn’t wait to shoot, and he one-timed a slap shot that went straight into the net.

Since then, BU hasn’t looked back. Soon, the Terriers had first place to themselves and they never relinquished it. One year after a 10-21-1 record — the worst a BU team has done since 1962-63 — the Terriers are regular season champions with a 21-7-5 record. They won their first Beanpot since the national championship season of 2009, and they are eyeing more hardware before the season is out.

The third-ranked Terriers can claim a second Hockey East trophy and a No. 1 seed for the NCAA tournament this weekend at the Hockey East championship at TD Garden.

Understandably, this dramatic turnaround has been reflected by what can only be called Eichelmania at Agganis Arena. Terriers home games have seen a sign depicting the Eichel Tower, featuring the freshman’s head crowning a drawing of the famous Parisian landmark. In an anachronistic tribute to president Dwight Eisenhower, BU has handed out “I like Eich” buttons, promoting the North Chelmford, Mass., native for the Hobey Baker Award.

All the while, Terriers fans have buzzed about the fact that Eichel is likely to be the second overall pick in this summer’s NHL Entry Draft, right after Canadian forward Connor McDavid.

Given the hoopla, you might expect Eichel to be, well, a bit of a prima donna. But the best news for BU has been that the 18-year-old has turned out to provide as much character as talent.

It’s fair to say that Quinn didn’t fully appreciate Eichel’s drive before he got to BU. It’s understandable: With his long, easy stride, Eichel can appear to be barely trying when you first see him skate. It’s deceptive, as he’s an explosive skater who can power past defenders before you know it — especially when the team needs him to step up.

BU has outscored its opponents by a stunning 62-22 margin in the third period this year, and Eichel has a lot to do with that.

“He’s as competitive as you’ll find,” Quinn says. “He wants to be the best player possible. He’s a great teammate. He wants to win, and not just for him. For all the notoriety and all the attention he gets, he just wants to be another hockey player. There’s no entitlement. With someone getting all the attention that he gets, it has the potential to be a nightmare. And it has been anything but.”

Eichel arrived at BU with nine other freshmen, putting the Terriers among the youngest teams in the nation. Between the leadership of last year’s survivors — who vowed “never again” after that dismal record — and the quick integration of the new talent, it’s a 180-degree turnaround on Comm. Ave.

“Our returning players were the key to everything,” Quinn says, noting that almost every Terriers upperclassmen has had a much better year than last season. “They were either going to embrace the group or not. Their attitudes to so many new players were going to either allow us to have success or was going to be disruptive.”

Of course, there wasn’t much point in clinging to the past. “It was also like, ‘Help is here,'” Quinn says. “And we have a bunch of guys who are confident but not ego-driven. We have a swagger this year, but it’s a respectful swagger.”

Along with captain Matt Grzelcyk, the overtime hero of this year’s Beanpot, Eichel is one of several Terriers players who have that oxymoronic “respectful swagger.”

“We just wanted to come in and try to be a piece of the puzzle,” Eichel says. “What’s made us successful is that everyone has found their role and realized what they have to do to help our team, and we’ve all bought into that.”

His whole freshman season has been a satisfying combination of work and play. “It’s been everything I dream of and more, playing at BU,” Eichel says. “It’s an unbelievable facility to play at, and then playing in front of great crowds every night. … I think I’ve matured off the ice and learned what I need to do on a day-in, day-out basis, and learn to manage my time. It’s part of being in college: No one is there to tell you what to do at all times.”

Although all college athletes are pretty swamped between classes and sports, there’s been no shortage of fun and hijinks off the ice. “We’re a bunch of clowns,” Eichel says. “We’re always playing pranks: Everyone’s always going after [senior Cason] Hohmann. He’s a goofy kid, and everyone picks on him. He and I go back and forth a lot at each other. I love the guy, but he’s pretty fun to pick on. It’s such a good team; there’s never a dull moment with these guys.”

Whether the team is enjoy the ritual of a weekly dinner at the Longhorn Steakhouse or razzing freshman Brien Diffley — “the weirdest guy on the team” according to Eichel, due to being a “really good painter who listens to weird music” and wearing “super-skinny clothes” — the team is clearly tight knit and having a blast.

“I think that translates to success on the ice,” Eichel says.

“They all have kind of a loose mindset, never really feel pressure,” Grzelcyk says of the freshmen class. “They’re really carefree, but when they get to the rink they’re really serious.”

As for Eichel, Grzelcyk points out that his work ethic has earned great respect. “He’s a fun guy, likes to have a good time off the ice and joke around with the guys, but he’s probably one of the most competitive kids on the team,” Eichel says. “He’s handled himself extremely well, staying after hours and working on his shot all the time. Guys really take note of that.”

Certainly, Eichel has not rested on his laurels as a top NHL prospect. Even though he’s so good — just try to figure out when he’s going to shoot versus pass — he’s always trying to get better.

“On the ice, I’ve learned to play away from the puck better and be stronger in the D zone and the faceoff dots,” Eichel says. “I’ve tried to bury my chances and work on my one-timer, and I’ve just gotten physically stronger off the ice. A lot of that has to do with our coaches; they’re so dedicated.”

Given all of the hype, Eichel has done an admirable job of keeping the NHL draft in perspective.

“I don’t go out of my way to look up who the bottom teams are or anything like that because there’s still a lot of time left,” he says. “I’m not looking past the rest of our season; I’m sure at the end of the season it will all take care of itself.”

Many have assumed that going pro this summer is a foregone conclusion, but that’s not a lock. “I don’t know,” Eichel says. “It’s going to be a decision made after the season.”

“I don’t think he’s rushing out the door,” Quinn says. “He loves BU, he loves his teammates and he loves playing here.”

Quinn says that there’s no question that Eichel will go straight to the NHL when he does go pro, and he believes that he would have statistical success immediately — maybe 35 or 40 points for starters. But that doesn’t make the decision a no-brainer.

“Because at 19? It’s a freakin’ hard league; I don’t care how talented you are,” Quinn says. “One thing I talked to him about is, you need to talk to Jonathan Toews, James Van Riemsdyk, Colin Wilson and Phil Kessel. Talk to people who were in your shoes — guys who stayed and guys who left. And I know what they’ll tell him. The guys who went back? The best moves of their lives. And the guy who left? Kessel regrets it to this day because it’s a whole different animal.”

That said, there will be no arm twisting from Quinn come late June. “I don’t want you to come back if you 80 percent want to come back,” he says. “That never works.”

In the meantime, what about winning the Hobey Baker Award as a freshman? Eichel leads the nation with 41 assists and 61 points to go along with a quickly earned reputation as a game changer. And it’s not as if anyone should assume that he’ll be around next year to win it.

The 10 finalists will be named on Thursday; voting takes places after the NCAA regionals and the award will be presented at Boston’s Matthews Arena on April 10.

“I’m a little biased, but how doesn’t he win it?” Quinn says. “He’s the best player in college hockey. If you talk to 58 college hockey coaches and say, ‘OK, who do you want to start your team with?’ Every single one of them is going to say Jack Eichel if you put them on the truth serum.

“I get the junior, senior, freshman stuff, but he’s the best player, bar none. I’ll be floored if he doesn’t win. After [Paul] Kariya and [Brian] Leetch, he’s the best freshman I’ve ever seen. I mean, the last guy who averaged two points per game in this league was almost 17 years ago [New Hampshire forward and Hobey Baker winner Jason Krog scored 53 points in 24 Hockey East games in 1998-99]. That’s freakin’ unbelievable.”

“He’s really the best skater I’ve ever seen with that stride,” Grzelcyk says. “He’s really a humble kid off the ice. You’d never know he’s going to be such a high draft pick, and he never showboats or anything, never talks about the draft. It’s just awesome to see.”

Given how hot Eichel has been all season, it makes sense that he hasn’t been feeling a draft. And there’s no question that he’d rather win the Hockey East championship, go to the Frozen Four and play on a national champion than win the Hobey Baker.

If you don’t know that, you don’t know Jack.