If preliminary ratings are used to analyze daily course difficulty, it's important to also adjust for average OB strokes per player each round. OB strokes artificially boosts the ratings. For example, in R1 total OB 33 for 100 players is 0.3 strokes added to "difficulty". R2 total OB 91 for 100 players is 0.9 added to "difficulty". R3 total OB 114 for 96 players is 1.2 strokes added to "difficulty". I heard that stats were not entered uniformly throughout the field, so these numbers are low if anything. Regardless, using the OB values as entered, it means R3 may have been even easier than the ratings indicate in comparison to R2, and R1 closer to the same as R2. Even if OB counts are correct, it still doesn't account for the strokes added because the conditions of some OB penalties involve marking at a drop zone with loss of distance resulting in effectively a 2-shot penalty such as missing the island on hole 17 with a minimal chance to save par from a drop zone a bit too far from the basket.