The "Mickey Mouse" ear-ball mold works pretty well with a split ring. If you use small hooks you may need 2 split rings.
There seems to be a perception among the fishermen I deal with that the football shape is better (for all things related to jigs)and that having no split rings makes jigs better. It's like the salt / no-salt debate.
The smallmouth in our Ozark ponds are killing the Mickey Mouse with a craw or beaver trailer when worked steadily along the bottom near rock transitions. Crank along the bottom, pause, stroke and BAM. Sometimes they nip at it, like bluegill (maybe it is bluegill??) while cranking it, but they hammer it when it tries to get away.!!