Quick answer: The hands arrive well ahead of the ball with the shaft leaning hard toward the target, like a grass chip; the club buries in the sand instead of gliding under the ball.
What it does to the ball
The leading edge digs instead of skipping: the club gets buried, the ball stays in, and the sand feels "heavy" even when it isn't.
Root causes (by frequency)
Hands too far forward, copied from the grass chip
Hitting down too much to "guarantee" contact
A closed face that cancels the bounce the sand wedge was built with
How to fix it
Let the sole do the work: hands level with the ball (not ahead of it) and feel the back of the sole bounce off the sand and come out the other side on its own
Drills that fix it
The bill under the ball · 15 min · 15 reps
Take a thin, consistent cushion of sand, letting the sole do the work Picture the ball in the middle of a banknote lying on the sand. Your job is not to hit the ball: it's to remove the whole bill — the club enters where the bill starts and exits where it ends, shallow and accelerating. Draw the rectangle in the sand the first few times as a visual reference.
The splash with no ball · 15 min · 20 reps
Accelerate through the sand with a full follow-through Without a ball, make bunker swings throwing a handful of sand over the lip onto the green: listen for the 'pfff' of the splash and finish with the hands high on every one. The flying sand is your ball. Once you throw 10 splashes in a row with a high finish, put a ball in the middle of the sand and repeat exactly the same motion.
Frequently asked questions
What is "Digging the leading edge (not using the bounce)" in the golf swing?
The hands arrive well ahead of the ball with the shaft leaning hard toward the target, like a grass chip; the club buries in the sand instead of gliding under the ball.
What does digging the leading edge (not using the bounce) do to the ball?
The leading edge digs instead of skipping: the club gets buried, the ball stays in, and the sand feels "heavy" even when it isn't.
How do you fix digging the leading edge (not using the bounce)?
Let the sole do the work: hands level with the ball (not ahead of it) and feel the back of the sole bounce off the sand and come out the other side on its own
Sources
Stan Utley (con Matthew Rudy) — The Art of the Short Game