It wasn't until this week at the league's pre-draft scouting combine in Buffalo when the two finally had a chance to sit down and chat.
"We've had a pretty good rivalry," McDavid said. "We've been linked together so long, you start to feel like you know him. And he's a nice guy."
The feeling was mutual for Eichel.
"Yeah, he's a pretty good kid," he said. "It was nice to finally meet him."
Just don't ask who's better between two centres who possess distinct styles, and are both regarded by NHL scouts as having "once-in-a-generation" ability.
"That's not up to me to decide," McDavid said. "I feel I'm the best player in the draft, but maybe you'll get a different answer from Jack."
Eichel responded by saying: "I'm pretty confident in my own abilities."
Officially, The Canadian-born McDavid finished first in the NHL Central Scouting rankings and is highly anticipated to be selected first by the Edmonton Oilers in the draft on June 26. He's a speedy, play-making 18-year-old who earned Canadian Junior Hockey player of the year honours after scoring 44 goals and 120 points in 47 games with Ontario Hockey League Erie Otters.
Eichel is the second-ranked prospect, and expected to be drafted by the Buffalo Sabres, who have the No. 2 pick. The American-born Eichel has a more hard-hitting style than McDavid and proved to be no slouch playing against older competition at Boston University. He led the nation with 71 points (26 goals, 45 assists) in becoming college hockey's second freshman to win the Hobey Baker award.
What's not up for debate is each player's ability.
"They both are going to be big contributors in the NHL," Central Scouting director Dan Marr said. "They're going to make a difference for their team. They're going to make an impact. They're going to put up numbers. And they're going to be special players."
The challenge for Marr and his staff was ranking the two.
"It's a fine line," Marr said, before noting McDavid earned the edge because he is regarded to have more potential.
"We feel the best is yet to come," Marr said. "There's still room for growth in his game."
Boston Bruins general manager Don Sweeney called both "foundational-type players."
McDavid and Eichel are among 120 prospects attending the weeklong combine, which concludes with physical testing Saturday.
Boston College defenceman Noah Hanifin is ranked third by Central Scouting, followed by McDavid's teammate Dylan Strome.
Hanifin acknowledged he would be shocked if McDavid and Eichel weren't drafted first and second.
"All they attention they've gotten this year, they deserve," Hanifin said.
Strome, meanwhile, had the best comment of the day, when asked how opposing teams might defend against McDavid.
"Good luck, I guess," Strome said.
Players spent the early part of the week holding one-on-one interviews with team executives.
McDavid had only had a few meetings, including interviews with the Oilers and Toronto Maple Leafs, who have the fourth pick.
He acknowledged being surprised in April when the Oilers jumped two spots ahead of Buffalo and Arizona to land the No. 1 pick during the NHL draft lottery.
"It was more shock than anything," McDavid said, noting he's prepared to play for whichever team drafts him.
"There's nothing to accept," he said. "If it's Edmonton, it's great. If not, it will be great anywhere in the NHL."
Eichel met with five teams, including the Sabres.
"I didn't do any preparation, to be honest with you," Eichel said of his approach to the meetings. "I think the most important thing about going into interviews like that is just be yourself, talk from the heart."
He's spent part of the week touring the city, and sampled some Buffalo chicken wings.
Eichel has not yet decided whether he'll turn pro next season or return to Boston University. He expects to make the decision following the draft.