Discovered this weekend that the Abarbanel translates "tz'fardaim" as crocodiles. Thus, according to him the second plague was not frogs, but something much worse.
In a way this explanation both fits, and doesn't fit.
Those of you who wonder why a swarm of frogs constitutes a plague can take refuge in the Abarbanel's explanation. However, you'll still need to tell us how the plague of crocodiles differed from "arov," the plague of wild animals.