Just four-plus periods into his NHL career, Vaakanainen has been sidelined by a concussion. The 19-year-old blue liner was charging hard to the Ottawa net during the first period when he took an elbow to the head from Senators defenseman Mark Borowiecki. Vaakanainen left the game and did not return.
The NHL Department of Player Safety tweeted on Wednesday that Borowiecki would have a hearing.
"[The league will] look at it. It's a flying elbow," said Cassidy. "Listen, I'm not in the heat of the battle. It looked fairly deliberate, he saw the player coming. But that's not for me to decide. It's unfortunate for Urho because he's concussed. But at the end of the day that will move up the food chain and someone will have to make a decision whether it's suspendible or not."
Already down Torey Krug (ankle), Charlie McAvoy (undisclosed), and Kevan Miller (hand), the Bruins will likely turn to Providence for reinforcements.
"I don't believe Kevan Miller will be available Thursday, Charlie I don't think either from what I'm hearing. Krug skated, too soon for him," said Cassidy. "We'll have to look at Providence, see what's the best fit for us, who's playing well down there and go from there.
"[Cody] Goloubef is a veteran guy there, he comes to mind; he's a right shot, so balance out the let and the right. [Matt Grzelcyk] and [John] Moore together, it's lefties. So if it's someone to play with [Steven] Kampfer that's a left stick, if it's Chris Breen that's played well, or [Jakub] Zboril, [Jeremy] Lauzon, whoever it happens to be.
"Their job will be to come up and probably play 12-15 minutes on Thursday and do a good job."