You may find that some of your shots are leaking right and/or arcing really high and falling short. If you're like me, you might be slightly (and unconsciously) flipping your left wrist and/or not leading with your left wrist at impact. It's important to understand what this feels like so that you can self-correct on the course. Flipping the wrist is definitely a high-handicap mistake that takes some work to resolve. Over time I have decreased the amount of wrist flip I had, but it was still there--wreaking havoc.
The incorrect feeling is one where the left hand knuckles DECREASE their distance from the top of the left wrist at impact, creating an angle between the back of the left hand and left forearm. This move is called dorsiflexion. At the same time, the right hand knuckles increase their distance from the right forearm (loss of dorsiflexion); as a matter of fact, the right hand is the culprit in causing the left wrist to break down. Sometimes, this flip starts early in the downswing in the form of casting: the backswing angles in the right elbow and right wrist are lost early. In other words, flipping is where the left knuckles get closer to the left forearm because of an improper backwards flexion of the left wrist and an improper forward flexion of the right wrist. The correct golf impact position has these two reversed--they should flip the other way through impact, if anything!
Flipping is an unconscious move that the mind believes will help square the club face and get the ball airborne. Of course, like many unconscious moves in golf, it results in countless, unintended errors, especially topped shots, fat shots, slices, and shorter, higher ball flights. This "left knuckles bent upward" lifting motion (even slightly) adds excessive loft to the club and effectively shortens the club length at the same time, and it's often associated with its evil cousin--coming into the ball with the side of the hand instead of the back of the hand (a face opening move that causes slice spin).
I posted previously on ways to square the club face, to include a leading with a bowed left wrist position, with the back of the left hand and left wrist aimed in the direction you want to start the ball flight. I have also posted about the "knuckles down" or "revving the motorcycle throttle" release as ways to think of this squaring, flattening action. Some instructors teach using your watch as a drill (i.e., make the watch face the target), but you can have the watch face the target with a flipped wrist. Remember, the goal is a flat or slightly bowed left wrist that faces the target. Ben Hogan said succinctly that he never saw a good golfer who did not have a flat left wrist (to slightly bowed left wrist) at impact; it's simply an absolute fundamental. There are numerous ways this feeling has been taught other than those I've already mentioned, including "thumbing a ride" with the left hand, "making the wrists kiss," leading with the left wrist into impact, going palm down to palm up, and on and on.
MANY reputable golf instructors say that this flattening of the left wrist and supination is not a result of conscious control during the swing but the result of the proper mechanics of what precedes impact. They say that trying to consciously "turn the knuckles of the left hand down" at impact (or other such manipulation) may result in a few good shots, but it's also a conscious manipulation that will result in many bad shots, because we're talking about the fastest part of the swing. It's also true that flipping the wrists is an unconscious manipulation that becomes a habit that must be unlearned. So the real question is how to unlearn the flipping...not how to learn the flattening or bowing.
I believe Hank Haney has the right approach to this problem. Instead of thinking of wrapping the ball inside a release by supinating the left forearm (which requires exquisite timing) to square the club face, simply concentrate on firming or bowing the left wrist at impact (which helps limit or halt the flipping motion) and making the back of the left hand face the intended target line at impact. After that, the release (or supination) will take care of itself. I prefer to think of leading with the left wrist. Shawn Clement states that trying to keep the club head low to the ground through and just past impact (like a chip) will stop the flipping motion and automatically apply a flat left wrist.
The inverse of the flat left wrist is the hinged right wrist, which should be cupped (or hinged backwards) during impact (see keeping the box). Straightening the right wrist happens during the release, when the ball is on its way. All of this is split-second stuff, which is what makes golf so hard. When the right wrist does straighten (and it should), the question is what should the left wrist do in response. The instinctive thing to do is the error--allow the wrist to cup or flip. The proper thing to do is allow the wrist to rotate backward (supinate), such that the "watch faces behind you ." If anything, the left wrist should bow through impact--not flip--becaue of the right wrist bending backswards more when impacting the ball and then the ground!
All this means one can think of proper fundamental simply by focusing on the left wrist or the right wrist, as they are analogous to one another during the golf swing.
You can produce (or purchase) training aids to help instill the correct feeling. A ruler (or similar rigid, flat object) placed under your watch can inform you if you're flipping; now the watch-facing-target-and-then-behind-you drill makes more sense. Michael Breed has uses the hanger drill to teach this feeling. But you can also simply take some practice swings where you're trying it both ways to learn what correct and incorrect feels like. This will help you ingrain the correct feeling and to realize when the incorrect feeling creeps back in.
The back of your left hand, assuming you've got a decent grip, will show you where the clubface is through impact. The common mistake a high-handicapper makes is swinging through the shot with the back of the left hand -- and the clubface -- pointed up. When the side of the hand leads the way like that, you'll hit weak slices.
Back to "impact," the more you turn your hand so that the palm is facing away from you, the better you square the clubface. If the palm is facing toward you, you'll leave the clubface open. The feeling you need is one of turning your hand almost to the point of palm upward. That's a hook swing, but not a bad feeling to have if you've been slicing.
In addition, the left wrist should be flat or bowed through impact. In the April 1956 issue of Golf Digest, Hogan wrote, "I've noticed one thing that all good golfers do and all bad golfers do not. The good ones have their left wrist leading at impact. It seems a small thing, but I've found it to be universally true. At impact the left wrist of a good player is slightly convex, while that of a poor player is generally concave."
This is all easier said than done. Proper supination with a flat or bowed left wrist is an advanced concept and one that it very difficult for the average golfer to learn. The vast majority of golfers instinctively flip their left wrists forward through impact believing that such an action will produce the optimal results: maximum distance and trajectory. Unfortunately, this couldn't be any farther from the truth. As with most things in golf, intuition must be thrown out the window. Instead, think of rotating your left wrist without breaking it.
Supination is the single most difficult thing to do. As Hogan said, the palm of the left hand must rotate to face up through impact. The left hand must also drive through without breaking down and allowing the right hand to take over.