Lazy man analysis. Like blaming Bonds for the San Fran Giants never winning a World Series.
Five forwards, at minimum, are non contributors. And I don't mean they don't score--I mean you're short handed when they're out there.
Outside pairing 3, the d can't shoot or complete a five foot pass, which eliminates both the rush and the cycle as methods of generating offense.
87's line is literally playing 2 on 5 hockey. Malkin's line, 1 on 5.
No idea how you manage to build a D that can't pinch, can't pass, can't skate, can't play defense, aren't physical and can't shoot, but it's what we've done, outside of green rooks and injured guys.