The Truth about Slope

Knowing the real meaning of the GAM/USGA course rating system can help you pick the right tees
By David Parsigian
We’ve all seen the golf magazine articles touting “Monster” courses that will make you cry in your golf towel. The problem is that most editors rely on a common misconception that “slope” is the one true indicator of difficulty. If you’ve ever been scared away from a course just because it has a high slope rating, read on. Michigan Links sets the record straight, but fair warning: There’s some math involved.

Golfers are masochists. Some love to test themselves by playing the most difficult course they can find — enduring torture from the tips rather than have fun from more forward tees or on a less challenging track. Contrary to the laws of nature, the path of least resistance holds no appeal.

Envy also plays a role. After all, if your friends have played the “toughest” course, lost a few sleeves of balls, and had to re-sharpen their pencils to count up strokes, you can’t let them suffer alone.

Given this desire for self-flagellation, golfers want to know which are Michigan’s toughest courses. Even more, they want to prove that their course is tougher than the one their buddies play. So what’s the answer? Well, it depends.

Now, you might interpret that answer as one worthy of a politician. Certainly, the Golf Association of Michigan is not in the business of telling members that one course is “better” than another. That’s subjective. But the GAM is in the business of helping members transport their GAM/USGA Handicap Index from one course to another to compete with others on level playing field. In order to do that, the GAM has to determine the difficulty of every golf course in Michigan. 

But the difficulty of every course is not the same for every golfer. It depends on the kind of player you are and the tees you choose to play from. So a single list of “tough” courses really won’t help. However, understanding what’s behind the USGA rating system can help you figure out what course is toughest — for you.

Bay Harbor, Hole Number 1

What do the Ratings Mean?
Many golfers (and magazine editors) believe “slope” is the best indicator of difficulty. In fact, that’s only partially correct. Slope is nothing more than a relative measure of difficulty. It allows you to accurately determine the number of handicap strokes you’re entitled to on any given course. More on that in a minute.

The true key to fulfilling your need for self-punishment is course rating. And while you can rely on the ratings published by the GAM in your pursuit of pain, you might like to understand how they’re determined.

Rating a golf course is a complex process based on data gathered and by observing real golfers on real courses. Ultimately, the rating is based on two factors: the skill of the player and the difficulty of a particular hole for players at that skill level.

Scratch vs. Bogey
Let’s start with skill. Based on the play of thousands of golfers, the USGA selected two standards: “scratch” and “bogey.” What’s a bit confusing is that they don’t mean what you think. A “scratch” golfer is not one who shoots around par and a “bogey” golfer is not at 18-over par. Instead, a scratch golfer is one who plays to the standard of play in the U.S. Amateur Championship.

Distance is a factor as well. The male scratch player hits tee shots an average of 250 yards, while the female scratch player hits tee shots an average of 210 yards. By contrast, a male bogey golfer’s average drive is 200 yards. He is not expected to reach a hole longer than 370 yards in two shots and he carries a Handicap Index between 17.5 and 22.4. For women, the bogey standard is an average tee shot of 150 yards, a two-shot limit of 280 yards, and a Handicap Index between 21.5 and 26.4.

This is essentially the set of standards for the “average” player. Not surprisingly, the scratch player is presumed to be not just longer, but also more accurate than the bogey golfer, particularly as the length of the shot increases. And while you might think that these standards are too modest given advances in equipment, the USGA is constantly updating them.

So how does the GAM determine the difficulty of a given hole for the “scratch” and “bogey” golfer? Each hole is evaluated in two categories: “effective” playing length and obstacles.

Effective playing length simply means the actual length of the hole, adjusted for roll (a measure of grade and firmness of fairways), elevation (downhill or uphill), whether a dogleg or a hazard requires the player to lay up, prevailing wind, and altitude.

With obstacles, things really get interesting. We don’t have room to explain all the factors and how they affect each other. But “A Short Obstacle Course” gives you a clue.

Who rates?
Course Rating System Inspires a Level of Trust

How can you trust the course rating system? For one thing, no club or developer may rate its own course; the USGA allows only authorized amateur associations to conduct a course rating. As nonprofit organizations with no prospect for financial gain, they assure that the final rating is dictated only by the features of the course.

In Michigan, the USGA has exclusively authorized the GAM and its more than 85 volunteers to preserve the integrity of the handicap system. Each volunteer receives extensive and continuous training, and must satisfy rigorous standards before they participate in a rate. A world-class GAM rating team also guarantees consistency in the process.

A Short Obstacle Course
On a course rating, the difficulty of each hole is a function of length and what the USGA calls “obstacles.” There are 10 different types of obstacles, and the importance of each depends on its severity, its proximity to the line of play, and whether it must be carried. For example, the location of an obstacle will likely dictate whether it comes into play for golfers at different skill levels. The rating system takes all these factors into account with a great degree of subtlety.

Here’s a brief summary of the 10 obstacle factors:

  1.  topography — Takes into account the effect of slopes and mounds on stance/lie, as well as any difference in elevation to the green that complicates club selection.
  2. Fairwa y width — Actual width in the landing area is adjusted for visibility, forced lay-up (or by choice), severity of rough, turf conditions, and factors affecting effective width, such as overhanging tree branches, tilt, severe obstacles on one side (e.g. out of bounds) or mounds that tend to kick balls back into the fairway.
  3. Green target — Measures the difficulty in hitting the green with the approach shot, taking into account the approach length and green size, shape, tilt, and any tiering.
  4. Recoverability and rough — Measures the probability of missing the target and the difficulty in recovering, taking into account rough height and proximity, lie, and elevation changes.
  5. Bunkers — Not just the number of bunkers, but their proximity to the target, their depth, and whether or not they must be carried.
  6. Out of bounds/extreme rough — Generally increases the rating of the hole because recovery is not possible or is highly unlikely; takes into account proximity to the fairway and whether there is enough room to avoid or to not have to carry.
  7. Water hazards — The rating depends on distance from the target and whether carry is required.
  8. Trees — The rating depends on the size and density of trees, their distance from the target, the length of the shot, and the degree of difficulty of recovery from the trees.
  9. Green surface — A function of green speed and contour.
  10. Psychological — A measure of the anxiety resulting from the cumulative effect of all the physical obstacles.

Setting the Ratings
Let’s put all this together. The USGA has weighted all of the factors for effective playing length and obstacles, and adjusted those weightings for how they affect the scratch and bogey player differently. Plugged into a formula with this weighting, the factors result in a different course rating for the scratch and bogey golfer.

The course rating represents the average of the better half of the scores of the scratch or bogey golfer under normal course and weather conditions. On a course rated 69.0 with a par of 72, a scratch golfer would be expected to post a 3-under-par score approximately 25 percent of the time.

Remember, a course rating is determined for both men and women on each set of tees. Where you begin will obviously affect length, but it will also figure into whether obstacles are in play. In general, though, length is the single most important factor in determining the course rating.

Slope and the ‘Bogey Rating’
So where does slope come in? Slope simply measures how much more difficult a course is for the bogey than the scratch golfer. The higher the slope, the greater the relative difference in difficulty. So if you perfectly fit the criteria for a bogey golfer, slope is a reasonably good measure of difficulty. But a better one is to use the course rating and slope to determine the bogey rating. Here’s the formula for men:

Course Rating (bogey) = Course Rating (scratch) + (Slope Rating ÷ 5.381)

For women, just replace 5.381 with 4.24

Like all the calculations involved in the course rating system, these constants are based on the play of real golfers. Once you’ve figured out the bogey rating, you’ll know that a bogey golfer will, on average, shoot that score about half the time.

Using Your Handicap Index
What if you’re not a bogey or a scratch golfer? Well, that’s the whole point of the course rating system. Your GAM/USGA Handicap Index is not your actual handicap for the course you’re playing. But armed with your Handicap Index and the slope rating, you can determine your Course Handicap from the set of tees you’ve chosen. Simply consult the USGA slope conversion tables  “Course Handicap Conversion

The more strokes you get, the tougher that course is — for you. But don’t be discouraged; every golfer plays to his Handicap Index only about 20 to 25 percent of the time and averages three more strokes than his Course Handicap.

So if you’re looking to maximize your frustration (and what’s golf without that?), look at both the course rating and the slope from the tees you plan to play from. They’ll tell you how tough is tough.

David Parsigian is an attorney with Honigman Miller Schwarz and Cohn LLP. He rarely plays the tips at his home course, Radrick Farms GC — a “tough” Pete Dye design.