Defensive player always switches - very annoying

Has anyone noticed that defensive players always switches the man their guarding? And it's not just on pick and rolls but all over the court. This happens all the time which is really annoying.

I'll make a basketball and all of a sudden my foward is guarding the point guard. Or I'll bring up the ball and the CPU's forward/center will be guarding for no reason. I would understand on a pick and roll but this just happens for no reason. Any suggestions on how to fix this?