If the angle of impact was from the stern quarter it doesn't
look like the Phalanx would have had much coverage.
Israel maybe very lucky in this instance and learn a lot
about how their construction holds up, fire control, etc.
Looks like the watertight compartments and damage control scheme worked, since the ship is still on top of the water and apparently still on an even keel.
You're right about the Phalanx engagement envelope - the Phalanx is mounted on the bow and a sea skimmer from a quartering angle would be occluded from the Phalanx system by the superstructure.
Maybe our naval architects will rethink their removal of Phalanx systems in favor of RAM launchers....