You are correct that he wasn't the lead singer. He was the originator I do believe.FYI- still sad but he was not the lead singer. Peter Wolf is the front man and is still alive and well.
J. Geils was the self annointed "best party band in the world" and it was well deserved. I much preferred their early stuff from Full House Live and Blow Your Face Out even though their commercial success came from Freeze Frame and Love Stinks. Hard Drivin' Man...Whammer Jammer...Detroit Breakdown...House Party...Lookin' For a Love. Epic.
The introduction from Musta Got Lost on Blow Your Face is epic and legendary.
My favorite is deep cut "Rage in the Cage" from the Freeze Frame album.