There is no denying that Coach Dave Cameron has done a fine job of guiding the Senators ever since taking over for Paul MacLean back in December.

Stepping up from the associate coach's position, Cameron was able to improve Ottawa's shot suppression (the biggest issue under MacLean, as I wrote about last year) and make better use of some under-utilized assets on the roster (Erik Condra, Patrick Wiercioch and Mark Stone, among others). Andrew Hammond's unusual hot streak in nets might have been impossible had Cameron not directed his players to really bear down and prevent opponents shooting the puck from high-danger areas.

Still, for all the things that Cameron and company do well, they are not without vulnerabilities. Mathematician, hockey researcher and Senators fan @IneffectiveMath pointed out to me recently, the Sens aren't very good at blocking shots, which I found interesting.

Delving deeper into the issue via video reveals that the Ottawa Senators are prone to breaking down when playing in defensive zone coverage.

Focus 1: 5vs5 D-Zone coverage

While the Senators are very aggressive when they have the puck, they tend to "sag" quite a bit when defending. On the one hand, retreating to the front of the net prevents those uber-dangerous cross-ice chances in the slot. On the other hand, it severely impacts a team's ability to block shots and leads to opposing players being open on rebounds. Here is a play from the Habs-Sens game on February 18:

Max Pacioretty has the puck down low and is pursued by Cody Cedi (OTT5). So far so good. Right-winger Bobby Ryan (OTT6) retreats to the hashmarks, instead of staying with Nathan Beaulieu at the point. In D-zone coverage, Red Wings coach Mike Babcock prefers for his forwards to "cut off the top," and prevent opposing forwards from getting the puck to the point. Instead of doing that, Mike Hoffman (OTT68) actually encourages Pacioretty to send the puck along the boards back to P.K. Subban. Meanwhile, David Desharnais has gained body position on Mika Zibanejad, who is unable to help. Bobby Ryan is still standing by himself in the slot, guarding a general area instead of a player in particular. Traditionally, the defending wingers are in charge of covering the opposing defensemen when they have the puck. However, instead of being tight to the points, the Senators' forwards are in no-man's land. Hoffman is stuck with Pacioretty down low, and Ryan is still standing by himself. Neither is in any position to prevent Subban from taking a shot, making a cross-ice pass to Beaulieu, or walking into the high slot. Subban goes for a half-slap shot through traffic. The puck goes through Ceci, who has failed to "front" the net man Desharnais, hits the post behind Andrew Hammond, and goes into the corner behind Jared Cowen (OTT2) and Dale Weise. Dale Weise beats Cowen to the puck and identifies a passing lane to Max Pacioretty in the low slot. Hoffman can't get his stick in the lane quickly enough, while Ryan and Zibanejad are once again guarding no one in particular. Pacioretty drops to one knee and gets good torque on his one-timer. Andrew Hammond makes a great reaction save despite being positioned on the goal line and not having time to come out and cut the angles. No goal here, but the type of prime opportunity that a team cannot afford to give up.

Focus 2: Penalty kill D-Zone coverage

Ottawa's younger, less experienced players can use their explosiveness to create open ice and convert scoring chances, but they also need more time and attention in order to learn how to make correct decisions on a consistent basis when playing inside set structure. Coach Peter Smith, who I work with at McGill, likes to say that "penalty killing is the most structured part of the game." This must be one of Dave Cameron's biggest challenges when coaching his special teams.

On March 12, with Ottawa down one player, a few minor miscues combined to create a P.K. Subban goal.

Subban is in control of the puck at the left point and Erik Condra (OTT22) comes out to meet him. On the ice with Condra are Jean-Gabriel Pageau (OTT44), Marc Methot (OTT3) and Mark Borowiecki (OTT74). Subban gets Condra to commit with a fake shot, then slides the puck over to Brendan Gallagher at the left sideboard. Borowiecki had retreated to the center of the ice to block a potential point shot, so he will be half a step slow getting to Gallagher. This allows the Montreal forward some time and space to create. The ideal option for Gallagher here is a cross-ice feed to Max Pacioretty for a one-timer. The Ottawa players know this and proceed to lock down the middle of the slot. Methot and Pageau double-up on the coverage, which prevents a scoring opportunity but also opens up seams elsewhere. To compound the issue, Condra's stick is out of position. He respects Subban too much and angles his stick to prevent to pass back to MTL76, but he would be better off guarding Markov instead, because that's a pass across the middle of the ice, much closer to the Ottawa net. Gallagher makes a good read and sends a hard pass right to Markov's tape. Condra swings back to cover the middle but it's too late, the puck is already on its way over. Note the positioning of Methot and Pageau. Normally, Markov would be Pageau's man, but the Ottawa forward had already over-committed to Pacioretty and can't get his stick anywhere near the pass. Meanwhile, Methot should be fighting to get in front of Pacioretty to tie up his stick, if need be. He is unable to do that and will be behind the 8-ball for the rest of the play. Markov might be getting old, but he is still as skilled and as smart as ever. Like a chess grandmaster, he reads the play in a split second and recognizes that Ottawa is in disarray. He absorbs the pace on Gallagher's pass and make a one-touch feed back across the ice for Subban. Meanwhile, Pageau's way behind on the play and Condra pivots the wrong way. He'll have to hustle and risk tripping himself up in order to have any chance of blocking Subban's shot. The situation has snowballed quickly against Ottawa. Their four players on the ice have combined to tie up 0.5 Montreal sticks (Pacioretty has body position on Methot and can still tip a point shot), Subban is getting a perfect one-time feed in a high-quality area (link to a previous post on the topic), and Andrew Hammond is fighting to get eyes on the puck. Very brave play from Condra, who slides in sideways in a desperate attempt to block Subban's 90MPH+ shot. Players' equipment is designed to protect mostly the front, so he'll be out for a while if he gets hit on the side of the knee, on the ankle or in the ribs. But Subban goes for a top corner here. If the puck were to hit the side of Condra's turned head, he could very well leave his life on the ice. Fortunately for Condra, Subban misses his head. Unfortunately for Condra's team, he does not miss the net. A 90MPH slap shot from 40 feet out will reach the goaltender in about 0.3 seconds. With the human reaction time to a visual cue being approximately 0.25 seconds, it means that Subban's shot will be nearly impossible for Andrew Hammond to stop. Power-play goal Montreal. FULL VIDEO:

And that's why it's so hard to play in the NHL. We've just spent the last 5 minutes dissecting a play which took place in less than 4 seconds. These guys are playing the fastest team sport in the world. Never forget that.

For the Montreal Canadiens to fully benefit from Ottawa's biggest systemic weakness, they will have to play a disciplined game, both in terms of drawing more penalties than they take, and in terms of possessing the puck in the Ottawa end. It will be tough to win playing run-and-gun hockey against the Sens, but if the Habs can hem the Senators in their zone, it will open up plenty of quality chances for their top-line talents.