This is an excerpt from Your Perfect Swing by James K. Suttie.
Generally speaking, a golf swing is either too high at the top and too steep coming down or too flat at the top and too wide coming down. For every swing I see too flat and too shallow, I see 10 swings that are too high and too steep.
Swings that are too high generally come down outside in. This is due to the early unwinding of the shoulder and torso from the top. The resulting shots are pulls, toe shots, pull slices, tops, slices, and shots that curve to the right. The correction for this is a lower swing plane at the top and less body action coming down. This creates a shallower, more inside approach to the ball. If you hit big divots that seem to go left of your target, you are too high at the top and too steep coming down. If this is you, do some baseball swings with your club, trying to get a feel for a flatter swing.
On the other hand, some of you may not get any divot with your irons. This usually means your swing is too flat and shallow, and inside out coming down. The shots you will tend to hit are hooks, pushes, thin shots, and fat shots. A lot of the marks on your clubface will be toward the heel. If this sounds like you, you will have to make your swing higher and use more body and less hands and arms coming down.
If you're better with your driver than you are with your irons, there's a good chance that you have a flat, wide, shallow, and inside-out swing. If you're good with your short irons and not so good with your longer clubs, there's a good chance you are like most of the golfing population: too upright, too steep and narrow coming down, and probably outside in through impact.
I hope this chapter has given you a good idea of where your swing is now as well as a solid understanding of the many factors that influence your swing. The next step is establishing or solidifying your swing foundation, which we'll work on in the next chapter. After that, we'll be able to slot you into categories based on your physical attributes and power source (chapter 5). But before moving on, I ask for your patience. Realize that old habits are difficult to build over, and ingrained swings are difficult to alter—but, you probably know this from years of frustration! To change your current swing, you need to recognize its strengths and weaknesses and understand how and why it developed as it has. This relearning process is like digging the weeds out of your front yard. If you cut just the tops off, they'll grow right back. We need to get to the root causes of your swing problems, but that's not going to happen in a short golf lesson. Finding your perfect swing is going to take some time. But stick with it—the journey is worth it, and you'll have fun along the way.
This is an excerpt from Your Perfect Swing.