“At the end of the year, there’s always players you don’t know how in the world you’ll ever replace,” Harvard men’s hockey head coach Ted Donato said after a season-ending overtime loss in the ECAC semifinals Friday. “But that’s the nature of the beast.”

Nothing was official at the time, but you have to think his mind was on his leading scorer. Center Ryan Donato had 43 points (26 goals, 17 assists) in 29 games for the Crimson this season, including two helpers in the semifinal defeat — and just so happens to be Ted’s son.

The younger Donato took another play out of his former Black and Gold father’s book on Sunday night when he signed a two-year entry-level contract with Boston. Now the Bruins officially have their top prospect on lock.

But where — and when — will he fit in on the roster?

“Ryan and his family had been thinking about what may or may not lie ahead, but they had been focused on the task at hand,” Don Sweeney said during Sunday’s conference call. “Once that was over, I had the opportunity to talk to [them]…we had always been committed to providing the opportunity to Ryan, and it kind of lined up.”

The Bruins burned the first year of his ELC — which is common when signing a highly sought-after prospect — and he’ll be joining the NHL club immediately. Even so, Sweeney was careful to avoid comparison with Charlie McAvoy, who vaulted into an injury-ridden lineup last season and exceeded even the loftiest expectations.

The signing does seem a tad serendipitous, with Patrice Bergeron (foot), Jake DeBrusk (upper body), and David Backes (leg) all out of commission and Donato’s experience playing both wing and center. The notion that he might jump right into the lineup doesn’t seem all that improbable. Although the Bruins’ GM doesn’t want to put too much pressure on the 21-year-old, Donato is eligible to play as early as Monday night against the Blue Jackets at TD Garden.

He probably will.

“Ryan will likely play as early as tomorrow,” Sweeney revealed. “I just think the injuries have presented time on the ice in game situations that, hopefully, he can take advantage of. He has the skill set, he can score goals…we’re gonna put him in situations where we can insulate him a little bit, and we’ll see where it goes.”

Unlike Trent Frederic and Cameron Hughes, who both signed recently with the Bruins but reported to the AHL, Donato had the opportunity to prove that he was NHL-ready on the biggest stage possible when he joined Team USA in PyeongChang for the 2018 Winter Olympics. If his standout career at Harvard and masterclass showing at the Bruins’ Development Camp earned him his contract, his Olympic run as the United States’ points leader (five goals, one assist) earned him the immediate roster spot.

“His being able to go over and have success at the Olympics really jump-started the thought processes that he was ready for the next challenge,” Sweeney said of Donato’s Olympic performance. “He’s got some confidence about him, and hard skill.”

Sweeney stressed that this is a no-pressure situation, an opportunity for the young center to “get his feet wet and prove that he can play at the NHL level” — and with good reason. The most promising prospects are still just that, until they actually make their way up to the hardest league in the world.

Even for Donato, a player used to tearing it up wherever he finds himself, this is going to come with unavoidable struggles.

“We have to fill in some of the gaps and details,” Sweeney said. “Our head coach [Bruce Cassidy] is very receptive to working with him…you don’t show up in the NHL having [every skill], you have to go through it. It’ll be a steep learning curve, but Ryan is a talented kid with a great hockey mind. I think he can handle it.”

Luckily, Donato will be taken under the wing of a head coach highly suited for his development in Cassidy. He is a skilled, smart goal-scorer whose main weaknesses are all on defense. Sounds reminiscent of David Pastrnak, who Cassidy has been able to work to the point where he avoids defensive sacrifices to, as Cassidy says, “do his stuff.”

Boston’s head honcho has also trained the fourth line of Noel Acciari, Tim Schaller, and Sean Kuraly to bring out their natural grit while honing them into one of the NHL’s most productive checking lines this season. Danton Heinen is another skillful first-year with whom Cassidy has implemented more than a few effective techniques to push through ruts.

So, to put it bluntly: if a player is going to jump into the NHL feet first, he wants Cassidy alongside him.

“He’s as good a skater with the puck as he is without and he’s processing very well,” Sweeney said of Donato’s skill set. “He played the center this year, he has power-play acumen, he’s heavy on the puck — when you have it, he wants it back, and when he has it, he doesn’t want to give it up…that’s rare.”

The 21-year-old, who the Bruins selected 56th in the 2014 NHL Entry Draft, still plans to finish up his junior year at Harvard and earn his degree.

“I am excited to announce that today I have fulfilled a lifelong dream, signing a NHL contract to play for the Boston Bruins,” Donato stated in a Harvard press release. “While I am beyond thrilled for this next opportunity, it comes with a bittersweet feeling as my time as a student-athlete at Harvard comes to a close…While [I am] no longer on campus, I am so proud to consider myself a member of the greater Harvard community, and I am still fully dedicated to working towards another lifelong dream of mine: a degree from the university that has given me the best three years of my life.”

There’s no reason why Donato won’t exceed expectations as McAvoy did last spring, and he’ll likely log some lengthy minutes over this stretch due to his versatility and the team’s current rash of injuries. However, there’s also no reason for panic or disappointment if he takes on more of a squad depth role when the roster returns to full strength. Cassidy has proved more than capable of youth development, but the process usually takes some time. Unless you’re Charlie McAvoy.

Or…maybe…Ryan Donato.