For a coach, video is often used to look at the symptoms of a bad golf swing. But if we’re being honest, if you aren’t using the data available to you to take a forensic dive into why things are happening, you might as well not use it at all.
In 2026, with platforms like Onform, there is simply no excuse for poor use of video anymore.
When I’m looking at a swing — whether it’s a Tour pro or an 18-handicap — I’m looking for specific red flags. These are the non-negotiables. By using the skeleton feature and 3D sway metrics in Onform, we can stop guessing and start measuring.
The Right Pelvis Post at the Top
When I analyze a student’s swing in Onform, I draw three critical lines: the right leg post, the left leg post, and the spine. These are my guidelines for identifying shift and pivot.
The first red flag is simple: If we take the player to the top of the backswing and the right pelvis joint is still to the right of where it started, that’s a red flag.
Every good ball striker moves to the right initially, but they must start re-centering in the backswing phase. Better players generally start re-centering before P2 when the club is parallel to the ground.
By the time they reach the top, I want to see that pelvis joint actually getting closer to the target than it was at address. If they are still stuck over that trail leg, they’ve failed to shift pressure effectively.
Failing to Re-center the Spine
I draw a line down the player’s spine at the start position. This is the baseline. As the player moves through the backswing, they’re going to shift, but the timing of the return is everything.
If the spine has not re-centered by the time the club changes direction at the top, that is a massive red flag. You’ll see it in the torso sway numbers.
A good player’s torso will start swaying back toward the target while the club is still completing the backswing. If that spine line is still tilted away or stuck back when the downswing starts, the sequence is broken.
I often hide the data and try to predict what the sway numbers will be just by looking at the skeleton. If I can’t predict the data, my eyes aren’t calibrated yet. It’s a great way for coaches to means-test their own principles.
Lead Shoulder at Impact
This is one of the most important checkpoints because the lead shoulder is the key element in determining the low point of the swing.
At the point of impact, if the lead shoulder is not at least back to where it started — and preferably slightly forward of that starting position — it’s a red flag.
For a player who wants to hit a draw, that shoulder needs to be forward. If the lead shoulder stays behind the initial line, the player is going to struggle to control the low point, leading to inconsistent striking because they can’t get the club to bottom out in front of the ball.
The ‘Target-Leaning’ Spine at Setup
Before the player even moves, the skeleton feature tells me everything I need to know about their setup. I look for the spine angle relative to vertical.
My baseline for spine angle at setup is about 87 degrees, meaning the torso is tilted slightly away from the target.
Anything where the spine is tilting toward the target at address is a major red flag. Unless a player has a physical deformity or a significant limb-length discrepancy, we want that spine neutral to slightly tilted back. If they start leaning toward the target, they’re already fighting a dysfunctional pivot before they’ve even taken the club back.
Improper Ball Position Relative to the Lead Shoulder
The industry has coached ball position relative to the feet for generations. I categorically do not do that. I coach ball position relative to the lead shoulder and the sternum.
Why? Because the lowest point of the golf swing is directly under the lead shoulder. I use Onform to drop a box from the lead shoulder down to the ground.
If the back of the ball is outside that box, either too far forward or too far back, it’s a red flag. If the ball is too far forward, the player will struggle to hit the ball and then the ground, and won’t get that necessary negative attack angle.
A Flat Shoulder Trace ‘Smile’
Onform has a joint tracking function that I love to use on the left shoulder (of a right-handed golfer). It creates a trace of the shoulder’s movement throughout the swing. I call this the “smile.”
Generally, the bigger the “smile” — the depth and width of that trace — the better the ball striker.
It indicates how dynamic the movement is. If that trace is flat or small, it tells me the player isn’t using the ground effectively and lacks the lateral movement needed to compress the ball.
Author Bio. Master PGA Coach Hugh Marr has spent two decades coaching at the highest levels of the game working with Tour players and serving as a Ryder Cup coach before turning his focus toward what he calls “coaching the coaches.” Through The Coach Alliance, Hugh has built a global network where coaches can learn from each other, compare notes, and keep improving.