I was told by people high enough up in that company to know, that Jack left on his own and the door was always open for him to come back.
Jack was an ad sales guy for the Lowell Sun back in the day, somehow he got his foot in the door at WJUL back in the late 70's and parlayed that into a stint at WLYN ( with another WJUL alumnus Rich Bono) and Jack just bounced from small market to small market station for the next 30 years.
His ego and perceived talent was always bigger than reality, a real legend in his own mind.
But he had the "good stuff" back in the day, and managed to screw his way through a good part of the WJUL female staff.