Here's a combination recommendation from Randy Petersen and Norm Duke.
Randy Petersen: point your toes slightly toward the direction you want the ball path to be, open your shoulders but during your down swing, lower your throwing shoulder below your non throwing shoulder. For me right handed, as my swing comes down, I am lowering my right shoulder, my left shoulder slightly higher helping me project the ball right. randy even said this on television Sunday, this is in contrast of what we have learned from years of being told to keep our shoulders paralell during the arm swing.Keeping the shoulder paralell works grea for down and in, but to move left and swing right, dip the right shoulder (right handed bowlers, opposite for left handed bowlers)
Norm Duke: This also helps with increasing ball speed. Right handed bowlers, left handed bowlers this is opposite.
After pushawayand during the backswing get the left hand/arm in front of youso your left arm is in front of you your chest is almost perpindicular to the line and your backswing will be much easier to get higher and it automatically has you in an open position.
What happens to a lot of bowlers that I coach is that they want to swing their off hand/arm around too much and too fast pulling their body around again making their shoulders paralell to the foul line causing them to pull the ball. I recommend watching Norm duke bowl and at home just stand there and put your non bowling arm out to the left and slightly behind you and you will see how this pulls your body around and tightens you upper body.
Good luck.
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Nicanor (Ten On The Deck)