As a former Pee Wee and Bantam coach, let me tell you that the hardest thing to teach players is to spend as much energy playing defensively as they do on offence. Unfortunately the glory, the money and most of the attention goes to the goal scorers... not the back-checkers... so players are alot more interested in expending their energy in the offensive end of the ice... and they are content to blame the defencemen or goalies when the team is behind.
My theory is that teams that spend their cap space on one-dimensional players don't win in the playoffs. Contrary to popular belief, players who make it to the NHL are capable of playing defensively. Some of them just choose not to, so if more than one of these one-d players ends up on the same line, and the coach accepts that kind of work ethic, then the team spends alot of time playing catch up.
Steve Yzerman, although a great offensive player, was one of these one-d players until he met Scotty Bowman, and Scotty turned him into a Hall of Famer... an all around player.
The big contracts should be reserved for all around players, so that when the game is on the line, a coach is not afraid of the high risk factor of having an all out offensive attack and nobody taking responsibility when the other team has the puck.
Teams that win the cup do so with a mix of players who work just as hard when the other team has the puck as they do when they are on offence.
PS: I hope Jason Spezza reads this. He could be one of those great all-around players.