Playing with some video last weekend.
Here is the (nearly) frame by frame sequence of a casting stroke that resulted in a tangled tailing loop. The anchor and D loop were both fine, but you can see that something happened and the rod tip (red dot) did not travel a straight line path. My analysis, which may be wrong: The problem was caused by an abrupt application of power early in the forward stroke and the rod was not loaded fully into the butt. The rod tip dips and then rises as a result - concave up rod tip path = tailing loop. On subsequent casts I managed to fix the problem, but I have a tendency to tread the fine line between a very tight loop and a slightly tailing loop when I'm going for distance with the Skagit kit that I'm casting here.
If someone has any other ideas, I'd love to hear them over on the Board.