Pizza Lord |
Yes, and the prone character's CMD would be at –4 because their AC penalty against melee attacks will apply to their CMD. Obviously, they aren't in danger of being knocked prone if the CMB check exceeds their CMD by 5 or more, but they're much less likely to stop the overrunning character.
Note, that Acrobatics checks to move through threatened and occupied squares are against a DC based on CMD, so these checks will also be easier.