I call it more lucky than anything. I'm not sure if Meph's drops have been nerfed. The patch.txt only mentioned Pindle, and Threshshock ( or whatever the hell his name is )
Andy does have higher chances to drop Rings and Amulets. Check out d2data.net for more info on the % for monsters to drop particular items. The chances are better but not by much. It still boils down to luck... But you can increase your chances by knowing what monsters are more likely to drop it.