The evolution of The J. Geils Band from their beginning as a blues band to their end as a massive pop band is a story best told by somebody who actually knows it.
The things I truly know about the The J. Geils Band are as follows: J. Geils was the guitar player, but despite the band being named after him, he didn’t write very many of the songs, which seems weird. Once they started writing their own songs, about three albums in or so, the bulk were written by keyboardist Seth Justman and singer Peter Wolf, whom I’m guessing that a lot of people initially assumed was the “J. Geils” of the J. Geils band.
Oh, and their harmonica player was Magic Dick, which is one of the five all-time greatest names ever in popular music.