For a guy who was supposed to be the next big martial-arts action hero, Jet Li has certainly settled for some shaky vehicles. And he's hit a new low with his latest, Cradle 2 the Grave, in which he plays a Taiwanese cop who teams with an L.A. jewel thief (DMX) to recover some priceless black diamonds. The plotline gets lost along the way, but the movie's real problem is its action. Hamstrung by poorly staged (and indifferently edited) fight sequences, the usually airborne acrobat comes off as just another B-movie martial-arts star. That's not what the studios -- or we -- are paying for. EXTRAS Two separate making-of docs discuss the elaborate lengths to which the production team went to ensure great fight scenes. Oops.