[Ravenous Bugblatter Beast]

I've started to think about the idea in a way that's more tactile to my thinking.

Instead of one-plane, I think of it as connected. Instead of two-plane, I think of it as disconnected.

A connected swing keeps the upper front arm close to the chest during the backswing; in order to do that you have to rotate around your spine. A disconnected swing will let the elbow increase the separation away from the chest and that allows a player to get a fuller swing without as much rotation as there is in a connected swing.

To work with a connected swing, you have to have decent flexibility down in the core area.