Malbim (14,15): They received three, corresponding to three sins (against Mitzvos Hashem, serving b'Shituf and denying Hashem). (a) They were given over to monetary plunderers. (b) Hashem removed His Hashgachah and left them to nature and chance, so their evil neighbors, who were stronger than them, overcame them. (c) He punished them overtly, in matters for which they should have succeeded based on nature.