Most people have hit on the big points that need to be addressed with the defense, so I'm going to take a little different angle with this. What is the thing about the defense this year that I hope 2K doesn't lose?
Well, I play a lot of Team Up mode, and people have to pick-their-poison this year. In year's past, people could camp the paint, play the passing lanes, double the big men, stop the drive, and recover to the corner to contest the jump shot. The recovery speed was so insane that they could literally just about cover everything at once. This year, if they help off their man, the drive and kick can be a thing of beauty. If they get inside their man's shirt, the driving lane or post up game is available. My teammates and I don't use the zig-zag tactic, so we've actually been able to run some nice offense this year by reading what the defense is giving us. This wasn't always possible in past games.
Obviously, 2K is going to get blasted with complaints about the "responsiveness" on defense, but I hope they can tighten up the defense controls next year while keeping the pick-your-poison aspect of this year's defense intact.

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