Ideally ads rotation sounds as a cool feature right?
However we tried that, and definitely that didn't sound to work with Facebook internal algorithm. We haven't had good experience in the past (yes, let's say "it wasn't good"), so is not a feature we are aiming to add to AdEspresso (as a matter of fact, we removed it at some point in the past).
We strongly believe in refreshing the ads after their performances start declining, but this should be done after comparing both frequency and overall ads performances. Also, based on the data we have, switching picture/text of the ad works better that pausing it and activate a completely new ad, give it a try :)