I'd say a 7-8.
The only difficult part of this game is winning five games online in a row. The matchmaking is piss poor in 2K12; you could be a prospect but be matched up against an All-Star. Reaching ten victories isn't an issue; it's winning the five in a row without having random crap get in the way which is tough.
Doesn't help that the online trophies cannot be easily boost as in 2K11.