The irony is in the name. Literally, “land of Tob” means “land of goodness.” But in spite of its name, Tob (northeast of Gilead) is not good for Jephthah. Here he has no home, status, or future, and he becomes the leader of a bunch of “worthless fellows.”
3 Then Jephthah fled from his brothers and lived in the land of Tob, and worthless fellows collected around Jephthah and went out with him.