Onetime Next Big Thing Brooklyn hoops product (and one-year Cincinnati Bearcat) Lance Stephenson was reportedly bummed the Knicks didn’t take him in the second round of April’s NBA Draft, and some analysts criticized the Knicks for taking two guys (Andy Rautins and Landry Fields) who were unlikely to be much help over the hometown kid. (He ended up with Indiana; both Rautins and Fields are expected to make the Knicks’ roster.) Well, this morning might have given some a clue to the Knicks’ thinking: Stephenson was arrested in Brooklyn for throwing his girlfriend down the stairs. The woman, 19, has a daughter with Stephenson, and told police “Stephenson pushed her down the stairs, and that she hit her head during the fall.” It’s not Stephenson’s first run-in with the law; he pleaded guilty to “groping” a 17-year-old girl last July.