Here’s the good news about the reports that the Rangers are closing in on signing winger Alexander Frolov: He’s a potential 30-goal scorer (he’s done it twice) who could skate with Marian Gaborik on the top line, and he should be motivated to play hard, as his agent readily admits that Frolov is seeking a short-term deal to essentially give himself a second crack at a contract season. The reason he needs that second crack, however, is that he’s known as an inconsistent player whose effort has been called into question at times. (After scratching him from the lineup last October, Kings coach Terry Murray described his play as “careless.”) Worth noting: The last time the Rangers acquired a player with the talented-but-enigmatic tag, it was Nik Zherdev, who scored enough points in 2008-09, but for our money was as frustrating as any player on that team this side of Wade Redden.