That's not really true, though? If you look at the PDGA rating system, it uses a generalized linear formula to compute a points-per-throw slope (based on rating) for the scoring spread of the field, based entirely on the determined SSA for the round. In general, this expected slope is fairly reasonable for most fields/layouts, however it's absolutely possible for this to skew the ratings. Basically, if the particular course/layout doesn't spread out the scores of the field as much as its SSA->points-per-throw slope says it should, ratings are going to be skewed lower (or higher, in the case of rounds worse than the SSA) than they 'should' be the farther your round score was from the SSA. If the particular course/layout spreads out the scores of the field more than its SSA->points-per-throw slope says it should, ratings are going to be skewed higher (or lower, in the case of rounds worse than the SSA) than they should be the farther your round score was from the SSA.