Pin placements, wind, rain, snow...all play a factor into ratings. That's why its hard to just have a score a certain rating on pins with multiple placements and played at different times of year. Matty-o shot 45 in 95 degree weather, no wind, I did it in 45 degrees and windy... not sure how that translates, but it does....
Take USDGC for example, That event is only done in early october. There's only a handful of weather situations that can happen and all the pins are always in the same local, Soooo you pretty much know a 68 is gonna be rated between 996-1003, Scratch golf.. It would be a very rare occasion if a 68 would be under 990 or over 1010...
maybe this is a bad example, but not sure how many people really understand the truth about ratings, not even the creator, Chuck Kennedy... It is the best thing we got... I would like to see it done in a different way...