Again, none of that accounts for a .4 PPG difference. That isn't "systems", or "defense vs. offense", it's skill and Crosby's abundance of it. There's also that Crosby is so good offensively that he's in the other team's zone most of the time. He drives puck possession so well that he isn't constantly holed up in his own zone. I get that you want to appreciate defense because the average fan over rates offense, I totally understand that, but when the offensive difference is so hilariously large you can't just throw it away by saying Datsyuk has to play defense (as if Crosby doesn't try to prevent other teams from scoring).
There's a stat that measures a player's +/- per 60 minutes of ice time. Crosby is at a 2.88, meaning for every 60 minutes he's on the ice, his team out scores the other team by 2.88 goals. For Datsyuk, it's 1.33. For every 60 minutes of ice time he gets, Crosby's team gets 2.88 more goals than the other team, while 60 minutes of ice time for Datsyuk leads to a 1.33 goals difference over the opposition.
That accounts for Datsyuk's defensive skills, as +/- adds a point for scoring a goal and subtracts one for allowing a goal. Datsyuk allows less goals per 60 minutes, but Crosby scores so many more points that when he's on the ice the Penguins will score 2.88 more goals than the opposition. This is objective statistics that takes both Crosby's offense and Datsyuk's defense into account. The object of hockey is to score more goals than the other team, and Crosby is creating 2.88 more goals than he gives up for every 60 minutes of time, while Datsyuk only creates 1.33.
http://hfboards.hockeysfuture.com/showthread.php?t=1382097&highlight=
I don't like doing this but this is the biggest hockey forum in the world, and in a poll for the best player in the league Crosby outvoted Datsyuk 147-3. And this is a board that hates him too, everyone calls him Cindy or a sissy or whatever, but they still recognize that he has currently unmatched talent. I love Datsyuk and he's one of my favourite players, but calling him better than Crosby is ridiculous.