There is a game where Matthews (and Nylander) are getting to their individual goals but it's driving team success, where they play the right way and offense flows from that game. The support cast was doing everything right in that first period, and they staked out a 2-0 lead.
You don't have to play a shutdown game with this kind of firepower. They could have just played dialed in and kept building the lead, let the milestones occur as they come.
That first shift by the Matthews line was sloppy sloppy sloppy, sloppy. Boosh with a terrible cross ice to Marner, a rushed dump in, sloppy center ice work by Matthews, random Brodie level stuff from Rielly turns into a scoring chance that our goalie wasn't ready to make a save on.