Note
This analysis is for fun! Please don’t take anything in this article too seriously. At some point, I’d love to do a deep dive on what makes a “proper” test and what it means for measuring player performance. For now, let’s get into the takes.
In my previous blog post, we looked at the Proper Test Index and a corresponding analysis identifying the most proper venues. What if we apply those learnings to player performance?
The theory is simple. let’s weight player scoring by the difficulty of the venue:
\[ \text{Proper Player Index} = \frac{\sum (\text{Wave Scoring Average} - \text{Score}) \times \text{Course Factor}^{*}}{\sum \text{Course Factor}^{*}} \]
When we do this type of analysis, there are some interesting consequences. Namely, there are some really low scores that don’t contribute to PPI because they come at courses that have never seen a score of 80+ from the professionals. In 2025 alone, there are 22 rounds below 65 that contribute nothing to a player’s PPI. Here are the lowest 10:
| Name | Score | Event |
|---|---|---|
| "Mitchell, Keith" | 61 | "Truist Championship" |
| "McCarthy, Denny" | 62 | "Truist Championship" |
| "Roy, Kevin" | 62 | "Puerto Rico Open" |
| "Gotterup, Chris" | 63 | "Puerto Rico Open" |
| "Bhatia, Akshay" | 63 | "Truist Championship" |
| "Morikawa, Collin" | 63 | "Truist Championship" |
| "Straka, Sepp" | 63 | "Truist Championship" |
| "Hughes, Mackenzie" | 63 | "ONEflight Myrtle Beach Classic" |
| "Matsuyama, Hideki" | 63 | "Truist Championship" |
| "Fowler, Rickie" | 63 | "Truist Championship" |
Yikes. Not a good look for Philly Cricket Club.
Comparison with Strokes Gained
From a Golf Sicko perspective, the most natural comparative metric for the PPI is Strokes Gained (Total). In theory, these metrics operate on the same scale, right? Let’s take a look at a 50-round rolling average of both to see if the PPI delivers any insight.
There are 4 categories in this visualization:
- Proper Players: above average players that rise to the moment
- Imposters: above average players that fall apart in difficult conditions
- Gamers: below average players that Step Up
- Mules: below average players that get worse when the going gets tough
In this visualization, there is one name that stands out to me: Justin Thomas. At the time of publication, he is the single player that suffers the most when we compare PPI to Strokes Gained. So what happened? Let’s look at a 50-round rolling PPI (red) alongside his Strokes Gained (Total; in black).
In the hover for this chart you’ll see “gain”. That’s just the difference between the wave average and the posted score with course factor applied. For example, if you shoot 68 with a wave average of 70 on a course with an adjusted course factor of 2, the “gain” is 4 ((70 - 68) * 2)
Oof. I know his pain. What we are seeing here is a combination of factors. First, there are 3 excellent rounds that fall off his 50-round average in this time: a 64 at the ZOZO, 63 at The Sentry, and 64 at the AmEx. Second, a good performance at the Truist went completely unrewarded (as mentioned up top). Finally, some poor play. 80 at The Memorial is punished massively; same with a 73 at The Travelers.
The PPI is unforgiving!