Hi mike vida, IMO it is probably getting too much water. Maples do not like constant wet feet. Let it dry out. They need to dry out between water. Too much water is so often the cause of a drooping maple. In your words, " it's getting plenty of water ". Other things to check as well is compaction of the soil around the base of tree, if it is then spike the compost to allow oxygenation of the roots. If it's in a pot consider raising it up on feet to allow better drainage. Hope that's of some help.
