Regular passing in 2K11 is close to useless. I'll try to simply throw the ball to my big down low, but instead, the player I'm controlling will attempt some crazy cross court pass that will either get picked off or go out of bounds.
Use icon passing and Total Control Passing instead.
Also, to stay on the subject, I do agree that practicing is key. I mostly use mkharsh's excellent Pro sliders because I find them more realistic, but I can win on default Superstar as well. Default Superstar used to make me want to throw my controller at the nearest wall, but I practiced until I was able to beat the CPU on that level.
All it takes is simple, down to Earth basketball, really. If you try to play streetball, you'll lose. Instead, you should call a play every time down if it's not a fast break situation, and even the quick plays will do. I love the basic pick-and-roll, for instance, because it often allows me to get some great looks at the basket. If the defense recovers or rotates, I'll give it to my big, attract the help defense, then dish it out to the open man for another good chance. If no help D comes, then I'll dunk it. That's 3 possibilities already, and if your big can shoot it from deep, then you also have the pick-and-pop, all that off a single quick play.
On defense, make sure you get around picks and play position defense. Also ensure that you don't give the CPU any mismatches, by using appropriate defensive matchup settings. In 2K11, defensive ratings matter a lot. You can't expect Scrub #411 to shut Kobe down effectively, no matter how well you play. Even if you put a hand in Kobe's face every time he shoots, he'll still make the shots because the player you're controlling isn't a very good defender. In the post, always make sure to put the biggest body on the opponent's best C or PF to avoid a certain barrage of post fadeaways.