The ball is “pinched” when the shaft is in line with the front arm, leading the club face at impact. Now, with my method, this is much easier because we use the body rotation to move the arms around to the left (right hander). If you are hitting chunky… you are either starting with too much weight on the back foot, or are moving to the back foot, and then not getting back in time… and “flipping” or throwing the club head at the ball… it is releasing (not good). We want to keep the 60% weight on the front foot during the backswing and you will not chunk the ball (ever).
Now, your thin shots are purely “flipping” for some reason. Many times it is because the back elbow gets stuck on the back hip as you are rotation (that flips the face)… that back elbow must lead on the downswing, back in front of the body and around to the left… THIS IS ALL DONE VIA THE BODY ROTATING. The body rotation brings the arms back down and around. This is harder to explain than do.
Move Less ... Get Good! DUPLESSISGOLF