Best way to understanding the jig fishing is to play around in ultra clear water such as pool or shallow dock. You'll see how much the trailers and skirting materials move with a little twitch.
Reason for stiff rod and low stretch line --- you need to 1. Turn the jig in the mouth 2. Pull the jig head out of locked jaws 3. Set the hook(the older the fish the more grissled the lip/jaw.
To understand how line stretch effects the hook set have your jig lift a bucket of 1/2 gallon of water over a rail while your back some 20 feet. Snug the line then pull the rod back until the bucket lifts. You'll be surprised to see how far you need to move the rod. Not all lines are the same.