i think he's playing maybe slightly bit worse than in '10-'11 before his injury. it's pretty close though. so this is second best or arguably his best season.
people also underrate his second season. he wasn't as complete a player then, but he was never "bad" defensively. he was so dynamic offensively that season. he's a smarter offensive player now, but that second season was a sight offensively that i don't if he's matched yet, in terms of explosiveness/sheer wow factor.
his '08-'09 season and even the rocket '09-'10 season were kind of lame, to be honest. he seemed much less explosive, slower, and looked too heavy out there. it's nice to have that rocket on his resume but i wasn't super impressed by his play.
i would rank seasons something like
1. concussion season
2. this season
3. art ross/mvp season
4. everything else.
it's also nice to see that crosby is finally starting to touch his real potential. imo crosby has the talent and drive to be a top ten (maybe higher) player of all-time, but injuries and crappy linemates have held him back. he has far too much talent to top out at 120 point seasons, imo.