Re: Rod grip style, and Lefty's principles
"When Lefty was talking about the shelf I believe he meant imagine your elbow sliding along a shelf and not static just sitting and pivoting on it. Sliding along a straight line like a shelf would help in forming a straight line path."
I agree, having had a lesson with Lefty. He stresses keeping the rod tip on plane and the "elbow on the shelf" promotes on-plane and tighter loops. A thumb on top grip promotes a smaller angle between the lower grip and the wrist. It is when this angle changes dramatically in the back cast, as I see in newbies, loops open and wrists quickly become sore. The thumb on top--as I see it--encourages the caster to stop at the top, use more shoulder and elbow motion and helps in keeping the change in wrist-to-grip angle to a minimum.