"Don't think Diana was at fault for how The Wiz turned out. Turns out Sidney Lumet stepped over his boundaries trying to produce a BLACK musical..."

Sidney Lumet was the director.
What "boundaries" are you trying to suggest?

Actually the way THE WIZ turned out lies directly at Diana's feet. Once she muscled her way into the leading role , the intended director, John Badham , no longer wanted anything to do with the project and bowed out thus taking the film's original concepts with him. He apparently wanted nothing to do with a film centered around a 30 something year-old woman playing the part of a 24-year-old teacher that' replaces the central part intended to be about a young girl .