Well, from what I understand, John Byrne had a problem with what he saw as Jim Shooter's heavy-handed editorial policies (strong inter-title continuity, the need to at least pay lip service to basic rules of signs, instituting line-wide crossovers, overruling the writers on plots and characterizations, etc). So when Jim Shooter was ousted, the EIC that replaced him hired a group of authors (that included John Byrne) to revamp and reinvigorate the stagnant New Universe line. John Byrne took over Starband, a title with a protagonist with many traits and background details that were similar to Shooter's and proceeded to turn Starbrand into a conventional superhero, have that backfire on him as he faced ridicule and lots of second-guessing, which, in turn, led to Starbrand trying to get rid of his powers, which resulted in a cataclysm that turned Pittsburgh into a pit full of mutagentic slime. Pittsurgh, btw, was Jim Shooter's hometown. Then, Starbrand's girlfriend died a rather gruesome death, Starband went insane and lots of other crap kept happening to him until the title was canceled.
From what I understand, many New Universe fans at the time accused John Byrne of sour grapes. I am inclined to agree.