Gryba received a two-game suspension for the incident that took place in the second period. Eller was left in an awkward position, looking behind him for a pass from teammate Raphael Diaz, when Gryba made contact.
"We do not see malicious intent by Gryba on this play. Eller is eligible to be checked and Gryba does not extend an elbow or launch into the head," Brendan Shanahan, the NHL's senior vice-president of hockey operations and player safety, said in a video posted on the league's website. "However, Gryba's route is not correct and we do not feel that he makes enough of a full body check for this hit not to qualify as an illegal check to the head.
"In our view, in attempting this very difficult check, Gryba does not hit squarely enough through the body. Eller's head is the principle point of contact and the subsequent contact to Eller's right shoulder is secondary."
Eller ended up face down on the Bell Centre ice, bloodied by the hit, was eventually taken off on a stretcher and spent the night in a Montreal hospital.
Eller returned home Friday morning after suffering a concussion as well as facial and dental injuries, the Canadiens said.
Saskatoon native Gryba was playing in his first career NHL playoff game. He received 15 penalty minutes in total for the hit, including a five-minute interference call that Montreal converted into one power-play goal.
Gryba's meeting with the league was expedited due to the fact the teams had games on consecutive nights.
He will be eligible to return for the fourth game of the series on Tuesday.
The Senators lead the series 1-0 heading into Game 2 Friday (CBC, CBCSports.ca, 6:30 p.m. ET).
Angry Montreal Canadiens coach Michel Therrien accused Senators counterpart Paul MacLean of "disrespect" on Friday for his comments about the hit.
Therrien said MacLean showed no compassion for the injured player when he placed the blame after Game 1 on Eller and Diaz.
Therrien spoke to the media prior to the league's announcement and was still seething about MacLean's comments.
"Inappropriate comment," said Therrien. "No respect for the player on the ice who was bleeding. No respect for his family in the stands. When he compared that to a hockey hit, the comparison he made was with the '70s, '80s and '90s. This is why we've got new rules, to avoid those hits when a player is vulnerable. That's why we've got rules.
"That was a lack of respect to Lars Eller and his family and I'm never going to accept that. Never."
After the game, MacLean absolved Gryba of blame and said players are taught to keep their heads up, comparing the hit to those dished out in earlier eras by blue-liners like Doug Harvey, Barclay Plager and Scott Stevens. He also said Eller should be mad at Diaz, who he referred to only as "No. 61."
Pass a non-issue: Shanahan
Shanahan said the Diaz pass had no impact on the hit.
"The pass that Eller received just prior to the check is completely irrelevant to whether or not Gryba delivers a reckless, illegal check to the head," he said.
MacLean said he was simply defending Gryba.
"Everyone was blaming my player for doing what he's supposed to do," said MacLean. "All I did was point out what happened.
"I feel bad for the kid that got hurt but that's what happened. It was a hockey play that went bad for him. If that's being harsh or cruel … that's too bad. Grow up."
Shanahan said some onus is on players to be aware of an impending body check.
"However, since the inception of the current illegal check to the head penalty, no player should expect that his head will be made the principle point of contact, whether intentionally, or as we feel occurs on this play, recklessly," he said.Suggest a correction