Why can people take a loss on NBA 2K11?

I have the platinum on the ps3 and yes getting quit on can get frustrating. I used OKC because they have Durant and Westbrook. KEEP THE GAME CLOSE!!!!!!! If you get to far ahead then they will quit. They are probably thinking *I have no chance now* so keep it close. Make sure you don't blow the game away though. That right there should let you go away with a lock in win!!! Good Luck :)