Just what is John Patrick Shanley, a major playwright and screenwriter, doing at the Chain Theatre, a black box on the third floor of a dowdy Garment District office building? Premiering a lesser work, that’s what. Much lesser. The Pushover, his frenetic new drama, might generously be described as an exploration of good vs. evil, a character study of troubled individuals struggling to wriggle free of the personas they’ve created for themselves, or a noirish crime caper. Mostly, what’s on the small Chain stage is three romantically entangled women, arguing, acting out, and pulling power plays on one another. It’s very loud, even without miking, and while there are intimate moments and the occasional arresting snatch of Shanley dialogue, the tone seldom varies from harsh and antagonistic.