Well the defense depends on the offense of your opponent...
there are alot of good defensive strategies, regular ones you know from bball in real life like man-2-man, zone or press-defenses and also some weird ones like "Hands-up"-defense-styles or just rushin for the Charge and alot of variations which player you control and which player is going for the help.
learn the defenses ea brings you with the game to play and create your own strategies. At best you play alot of games versus different players to see which defense works best for you and against which D you got most problems.
At last, i wanna get back to my first sentence, you are available of some defense strategies, use them in the game and watch for, which one works best against your opponent.

But every D has its weakness, if it fails switch it!