This post is following this discussion on DeCode Ingress community on Google+
It seems that Niantic changed logic of how the XMP works. Some of the community members saw that even if you stand directly above resonator it will not give it highest damage. This is not the case from before the field decay event so we can assume that logic is changed.
There is also theory that XMP do more damage to resonator that are in front you, so that XMP do more damage on 120-180 degrees and a lot less to resonators that are behind you. This makes huge game logic change, because it would be easy to focus few high level attack to wipe out portals that are lined up.
Did anyone had more experience with this? What about high level XMP’s?