That team was the Caps. The winning team was the Canes. That means we get a Game 7 at Capital One Arena on Wednesday night.
Here's my spin: It's a bad rule and a bad interpretation. From the reverse angle via NBC Sports Washington's coverage, you can see Ovechkin's stick making contact with Mrazek's pad first and then the puck trickles in behind Mrazek.
We could not see for sure if Ovechkin's stick actually made contact with the puck after that, but it's believed that it did.
The momentum of Ovechkin's force from crashing the net does contribute to the puck going in behind Mrazek, but it's not the typical definition of goaltender interference, which would result in a two minute penalty for the player that interferes with the goalie.
The NHL is saying that the goal was scored because of the interference. However, Ovechkin's contact didn't prevent Mrazek from making the save, in my opinion, as is standard for goaltender interference. This is an extension to the rule.
Mrazek did not have full control of the puck behind him and the play was not whistled dead, allowing Ovechkin to poke at what he interprets as a loose puck, without a whistle blowing the play dead..
If he doesn't interfere with the goaltender's ability to make a save (he didn't) and the play had not been whistled dead, some contact in the crease has to be allowed.
Rules are rules, it doesn't mean that they are good rules.
For our "Five Duds" of the night: