Strokes gained, explained

1. 1

   The baseline

   From the tee of a 400-yard par 4, a tour player needs about 4 strokes on average. From 150 yards in the fairway, about 3. From 20 feet on the green, about 1.9. Those averages, for every distance and lie, are the baseline.

2. 2

   One shot

   You drive it 250 to the fairway, 150 left. Expected before: 4.0. Expected after: 3.0. Strokes gained: 4.0 − 3.0 − 1 = 0.0. An average tour drive. Drive it 280 to 120 in the fairway (expected 2.8): +0.2. Into the trees at 180 (expected 3.5): −0.5.

3. 3

   The categories

   Tee shots on par 4s and 5s go to off the tee; par-3 tee shots and everything to the green go to approach; anything within 30 yards of the green's edge to around the green; putts to putting. Tee to green is the first three. Total adds putting.

4. 4

   The reading

   A round at −6 total split −1, −3.5, −0.5, −1 says the strokes are in the approach shots. That is where the practice goes, not the putting green.

The baseline is a choice. Against the tour, everyone is negative; the information is in the differences between categories and between rounds, not in the sign.

From your shots, not from the card. When your rounds come from a Garmin watch connected to Badgie Golf, each shot has where it started, where it ended, the distance and the lie: exactly what the formula needs. The engine scores every shot against a scratch-level baseline table built on Broadie’s method and adds them up by category over your last rounds. Two honest limits: putting only counts when putts are recorded (Garmin’s automatic shot detection usually stops at the green, so putting reads neutral), and the baseline is a scratch benchmark, so your numbers are negative and the read is the comparison between categories. On WhatsApp Morris gives you the category that costs most and the one thing to work on; the swing analyzer finds the cause behind an approach game that leaks, and the handicap calculator shows what a round would do to your Index.