Marcus Smart can’t help the Boston Celtics on the court right now, but he’s doing his best to remain accountable off it. The Celtics guard, who’s been sidelined since Jan. 24 after injuring his hand in a losing battle with a picture frame, took part of the blame for Boston’s recent rough patch in his second public comments since the incident. “I’ve been on myself pretty bad,” Smart told The Boston Herald’s Steve Bulpett on Wednesday night, “especially when I have to just sit back there and watch those guys struggle, and there’s nothing I can do. But we’ve got the break coming up. We’ve got to come back and be ready.”