That's where I think this rule will be problematic. A lot of tackles are made with the tackler wrapping (and not necessarily from the back as someone mentioned before) and the legs kicked and they drop their weight. I guess the key will be if they land on the back of the players legs. In the video highlights of our new linebacker, Gay, used that technique about three times. I'm not saying these will fit the league's definition of a "hip drop tackle" but that is the ambiguity I'm concerned about, i.e. "was that a hip drop tackle" and "was there enough contact with the back of the legs to warrant a penalty" etc. We'll see if the rule passes at all and if it can be defined properly to minimize interpretation.