CMB and expertise

hey can someone give me their thoughts on if the - u get from using expertise effects moves like grapple if you are defending against them?? so if fighers attacks using expertise then foe tries to grapple him does he get a minus or bonus to his DC??

As it is, expertise doesn't affect combat maneuvers. But that's a good point; if you're focusing on defending yourself, why doesn't your CM DC (combat maneuver DC) go up?