The Golden Knights defeated the Ottawa Senators 5-1 later Thursday. Robin Lehner, a former Buffalo teammate of Eichel, made 38 saves for Vegas.
"It's been a pretty, pretty big day, right?," Lehner said. "First of all, best of luck to [Krebs] and [Tuch]. Two fantastic teammates. Unfortunately, that's part of the business. ... But this organization, if there's an opening into what they think will make us better, they do it.
"I played with Jack, and obviously I've been talking to him quite a bit the last few months here. First and foremost, I'm just happy for him. He gets to go and take care of his body his way. I think that's a big step for all of us players in the league, that we respect his choice. I wish him the best in recovery. And as for him as a player, he's a world-class player. I've played with him for a few years and I've seen what he can do, and ... when he's healthy and he's on his game, he's up there with anyone."
Pietrangelo said Eichel would boost the offense, which was 29th in the NHL in scoring (2.22 goals per game) entering Thursday.
"He's one of the top forwards, top centermen in the entire NHL," Pietrangelo said. "If you look at how he complements the other guys up front, that's going to be a huge part."
The Sabres (5-4-1) have lost three in a row after a 5-2 defeat at the Seattle Kraken on Thursday. Buffalo was last in the NHL standings last season and missed the Stanley Cup Playoffs for an NHL-record tying 10th straight season. It lost 18 straight games (0-15-3) from Feb. 23-March 29, the final 11 without Eichel.
Tuch hasn't played this season after the 25-year-old had shoulder surgery in July and was expected to need six months to recover. The first-round pick (No. 18) by the Minnesota Wild in the 2014 NHL Draft has scored 139 points (61 goals, 78 assists) in 255 regular-season games for the Wild and Golden Knights, and 33 points (19 goals, 14 assists) in 66 postseason games.
"Alex is a very good hockey player, proven in this league," Adams said. "Under contract for this year and the next four years at a young age, and a very productive player. And high character, leader. All the intangibles."
Krebs is without a point in nine games with the Golden Knights this season. The No. 17 pick in the 2019 NHL Draft has played for Vegas, Henderson of the American Hockey League, and Winnipeg in the Western Hockey League the past three seasons. The 20-year-old scored 43 points (13 goals, 30 assists) in 24 WHL games last season. He will report to Rochester of the AHL and play his first game on Friday.
"... Obviously, you have mixed emotions, but I'm excited to be here," Krebs said Friday. "It's an awesome opportunity. Everyone here is opening with great arms and I'm excited."
Adams said he the Sabres can be patient with Krebs' progress.
"This is all about the long term and about building this and about developing this the right way," Adams said. "He's a really good hockey player right now and we're excited about the hockey player he's going to become over time, and that's our focus. When it's the right time, he'll be here and he'll be here for a long time."
The Golden Knights played Thursday without injured forwards William Karlsson (foot), Mark Stone (lower body), Max Pacioretty (lower body) and Nolan Patrick (upper body), and defenseman Zach Whitecloud (upper body).
"I think you can't look short term when you have an opportunity to get a difference-maker," DeBoer said. "This guy (Eichel) is 25 years old. Those guys are never available. The opportunity to get a guy like this is very rare. I think the way you have to look at it is, if he's not in the situation he is, is he even available? The answer is, probably not. That's the price you've got to pay short term, and I'm confident in our group that we're going to scratch and claw and keep ourselves relevant."
If Vegas selects in the top 10 in the 2022 draft, the first-round pick in the 2022 draft becomes an unprotected first-round pick in 2023 and the second-round pick in 2023 moves to the 2024 NHL Draft. The third-round pick from Buffalo would then move to the 2024 draft.
"I wish him the best, I really do," Adams said of Eichel. "I think he's in a really good spot. And I think we got a really, really good return in a really challenging situation that we can move forward with in our organization. That's what I'm thankful for and thinking about."
The Sabres on Thursday also acquired defenseman Johnny Boychuk in a trade with the New York Islanders for future considerations. Boychuk sustained an eye injury in March 2020 and did not play in the NHL last season. He is in the final year of a seven-year contract with an NHL salary cap charge of $6 million.
"This move is important because it gives us flexibility throughout the season from a roster perspective," Adams said. "There are different conversations that we've had with many teams. The key for us was to give us (salary cap) flexibility without compromising where our current roster stands."
NHL.com independent correspondents Heather Engel and Danny Webster contributed to this report