Radak: Yo'el was the head of Bnei Gad; all four headed families and ruled in Bashan.

Radak and Malbim, citing Pesachim 68a: Shafat is the father of Elisha ha'Navi. He is mentioned next to Bashan, to teach that just like there were 60 cities in Bashan, Elisha led Yisrael for 60 years.

Malbim: Yo'el was the head of the Shevet, like it says above ¹ (4); the Nesi'us began with him. Shafam was second to him. Verse 7 said that Ye'i'el was the head, i.e. in the days of Yosam. It seems that he was only the head of a family, but not of the entire Shevet, for he was not in the chain of Nesi'im from Yo'el until Be'erah (4-6). Or, perhaps Ye'i'el was Nasi ha'Shevet; initially, he was omitted. These were the heads in Bashan when Gad spread to there.