Wiercioch and Cowen play against roughly the same competition as Methot and Karlsson. They also get roughly equivalent offensive zone starts. Phillips and Gryba are our "shutdown pair", and they're heavily outperforming the 2nd pairing in the possession department.
Cowen, so far this season, is leading the league in shots against per 60, despite getting fairly high o-zone starts. While Karlsson and the third pairing aren't playing that great this year, the main problem on our D is that second pairing.
Yeah, the second line is definitely a problem. Oh wait:
The second line is getting the toughest defensive starts and the toughest competition, and they're dominating shot attempts. Every other line is getting killed, despite getting easier starts and competition. I'm pretty sure the main differences between that line and the other 3 are zone exits and neutral zone play. Whenever the Turris line is in our own zone, they're passing it quickly out of the zone, AND they're gaining the offensive zone with possession. In contrast, the bottom 2 lines tend to stay hemmed in our zone for longer and then play dump and chase when they do get it out (often resulting in a turnover), and the top line gives away the puck a lot in transition.
e: Also, aside from the first line getting outshot, it seems like they're also giving up a lot of really quality scoring chances. While Spezza's leading the team in scoring, he's also leading the team in goals-against while he's on the ice. So far this season, at 5v5, he's sitting at 5 goals for and 7 goals against, and many of those can be traced to crappy turnovers and bad decision making. On the flipside, Ryan, Turris and MacArthur, who lead our forwards in 5v5 TOI/game, have only been on for 4, 3 and 2 goals against, respectively, despite also eating up the most defensive draws and playing against other teams' top lines. Turris and MacArthur, by the way, also lead the team in goals-for at 5v5 while they're on the ice.
NOTE FOR INTERPRETING THE ABOVE GRAPHS:
The x-axis is offensive zone starts (further right = more o-zone starts)
The y-axis is quality of competition (higher on the y-axis = tougher competition)
The colour of the circle represents positive or negative shot attempts (blue circle = you outshoot the opposition; red circle = you get outshot by the opposition)
The size of the circle represents shot attempt differentials (bigger circle = bigger difference in shot attempts. Big blue circle = really good, big red circle = really bad. Small blue circle = okay, small red circle = sort of bad)