The fury of the Lesser Elementals couldn't be underestimated. They didn't care about surviving and were willing to sacrifice themselves if they could eliminate as many Kitsun as possible. Even if their lives ended after they took down as many enemies as possible they would be satisfied.
But since there were more than 3000 Lesser Elementals, and Michael's army consisted of 1500 combatants, it was hardly a problem to kill a thousand Kitsun Summons and a few dozen Awakened. They used their numerical advantage to eliminate the Kitsun one by one, all while Michael focused his full power on eliminating the stronger Awakened.