[thejeff]

I think it's a little more complicated.
From the FAQ:
# The chance to heal a battle affliction differs for each of these units and some afflictions are more difficult to heal than others (Never Healing Wound being the most difficult). Healing works so that the number you see is the chance to successfully use a healing ability that turn. If the check is successful, it checks against the difficulty of the affliction and if that succeeds as well, the affliction is removed.