Point your trail-elbow funny bone at the ball
To fix a trail (right) elbow that flares out, Porzak cues the feel of the funny bone pointing more at the golf ball rather than flaring back behind you. He gets the hand under the elbow and 'pinches' the elbow toward the center of the body, holding it in that position. The feel keeps the trail elbow in front and toward the body instead of splaying away.
Channel: PorzakGolf
Watch official source at 4:31