When the Avalanche found themselves tied in a game without goals entering the third period yesterday, there was plenty of hope the team could find a way on home ice to come out on top of the St. Louis Blues. They had played a tightly contested defensive game and goaltender Semyon Varlamov had been great at bailing them out of the breakdowns that did occur.

Things changed just minutes into the third, however, when Colorado’s top line yet again found themselves on the wrong end of a game-changing play. This is what I’ll be breaking down in this edition of the Avalanche Film Room.

Colorado has been very comfortable matching up their top line against opposing top lines this season, largely because the defensive play of Gabe Landeskog has been legitimately elite. While Nathan MacKinnon and Mikko Rantanen have a tendency to get lost and do more puck-watching in the defensive zone, it’s Landeskog who has been the rock for them this year. Given what happened in this sequence, I can’t help but wonder if he knows that, too, and the key decision he made that cost them is one he wouldn’t have made had there been more trust of his linemates.

Tarasenko’s escape

The sequence begins with Vladimir Tarasenko with the puck. Landeskog is marking him and forces him wide of the net and ultimately to give up the puck. Given Tarasenko is the most offensively gifted of his linemates, this should be considered a good thing. Tarasenko then disappears behind the net and skates to the other side of the ice, where Landeskog initially follows him. As the skip ends, we see Landeskog loosely keeping near him but not committing to him too much as Tarasenko drifts off the screen and away from the net.

To be honest, all of this is a win for the Avalanche up to this point. Tarasenko has given up the puck and removed himself from not only being a threat to score but from the play entirely. As we’ll see below, that’s exactly what he was hoping to do.

Landeskog’s abandonment

This is where the Avalanche gets into trouble. You’ll see Colorado’s four players not named Landeskog rotate as they’re supposed to and each has their responsibilities marked. Barrie has the puck carrier, Brayden Schenn, and Johnson is keeping in front of Ryan O’Reilly but not so close O’Reilly feels comfortable leaving the wall. MacKinnon is guarding against passes back to the point, as is Rantanen keeping a loose eye on Colton Parayko. Schematically, the Avalanche did what they were supposed to here.

Barrie knocked O’Reilly down, switched onto Schenn and Johnson moved to pressure O’Reilly when Schenn, who was about to be doubled by a collapsing MacKinnon, dropped the puck to O’Reilly. This is where Landeskog makes the critical error.

If you go back to the first gif, it leaves off with Landeskog trailing Tarasenko as Tarasenko drifts away from the net. Landeskog apparently decides this is a good time to apply a secondary pressure on O’Reilly, even though Johnson has him marked and is skating towards him. To my eye, there simply isn’t a legitimate upside in what Landeskog is trying to accomplish here, especially because he never motioned or communicated to Rantanen to keep an eye on Tarasenko, so there was no switch in assignment from Rantanen here. Tarasenko has now worked his way back into the play after he saw Landeskog completely leave him alone.

The goal

O’Reilly finds the seam between four Avalanche players as Barrie and Rantanen had sagged off their assignments just enough to try to make a play with their stick. Neither really come close. Tarasenko receives the puck and despite Varlamov squaring to him with as aggressive a posture as he’s able to manage in that situation, Tarasenko reminds the world why he’s one of the premier goal scorers.

Landeskog is caught in no man’s land as he ends up covering nobody and unable to make a play with his stick both on the pass and shot after he completely left his coverage wide open. This ended up being the game-winning goal for the Blues, who earned their ninth consecutive victory overall in beating the Avalanche.

Rotational failure

This reverse angle gives you an even better look of just how far Landeskog drifted away from his assignment. That Rantanen’s spidey sense was apparently tingling enough to cause HIM to drift down towards the play is interesting more than anything else. It shows good instincts from Rantanen but in sticking to his assignment, he wasn’t comfortable enough abandoning ship entirely. It’s hard to blame him. Keep in mind Parayko is the guy who scored two goals in the December matchup in St. Louis. Leaving him unattended would have also been a bad idea.

The real breakdown here came from the player you’d least expect to be irresponsible – Landeskog. He’s had a season worthy of being involved in the Selke discussion as his on-ice results have been extremely impressive. Unfortunately for Colorado, the wheel of misfortune landed on his name yesterday and he made the mistake that opened the scoring early in the third period. The Blues scored again just minutes later and cruised through the rest of the night en route to a 3-0 victory.

Colorado’s defense and goaltending have taken a lot of flak for their struggles this season but this is a good example of just how much of a five-man game defense really is and how one poor read can cause a ripple effect of breakdowns with the rest of the unit.