The way I'm taking it, is they implimented an actual physics engine to help drive the game. It wouldn't make much sense for it to just apply to hitting and nothing else. Really the only issue with 10 when it came to puck physics is it didn't bounce as realistically and as much as it would in real life other than that 10's puck physics weren't all that different than 2k10's the difference being 2k10's puck would unrealistically flip all over the place for the sake of flipping more often than not yet strangely remained glued and magnetic to player's sticks, even at times said player was checked flat on his tail end.
Hard to say if its real world physics or something more akin to something like the physics engine Backbreaker employs though I would be inclined to guess its prolly something in between. If it makes the game play better or react in a more realistic fashion, I'd say thats a step forward.