Using common sense, what's the difference between a Ref save and CMD? In one, you are dodging area of effect or such like, and in the other you are dodging trips and shoves and such like. Aren't you doing the same thing then? From a common sense viewpoint, not neccessarily from a rules perspective, why are there two separate things for ref saves and CMD?
CMD is not simply dodging/evading, it is just as much resisting a combat maneuver.
Resisting a disarm attempt is as much to do with maintaining a firm grasp of your sword than moving your sword out of the way.
Similarly, your opponents attempt to escape your grapple is against your CMD. This is clearly not, because your slip away from him, but because keep a strong hold of him.
The same goes for the most of the combat maneuvers. From a common sense perspective, I think they are quite far from the reflex save.
Imagine someone trying to grapple or trip a collossal dragon, versus trying to catch that dragon in a fireball.
What is this "common sense" thing? I keep hearing the monk, the cleric, and the druid telling me to use it.