James -
To address the last question you raised, the Slope Rating makes no attempt to factor in how course conditions at different times of the year might impact scoring.
DT
This has always bothered w/r/t slope rating. Two of the factors used are green speed and the severity of rough and yet those conditions can change day to day let alone throughout the season.
This isn't entirely true ... have you guys ever played with the raters?
They ask all sorts of questions about what the " average " conditions are in comparison to how they are that particular day. It's certainly an imperfect science, but the raters do their best to find out what the average conditions are. Courses that have significant changes from one part of the year to another , will certainly be skewed toward the season that the raters are playing the course. Believe it or not, so will how the rater plays that day. Human nature only dictates that if he/she makes a lot of putts one day he will think the slopes in the greens aren't so bad, as opposed to a day where he/she miss everything, thinking the greens are tricky.
There also is a problem with course ratings, they are based on a scratch golfer, as it was defined a long time ago with an average drive of 250 and able to reach 470 holes in 2 shots. I have had conversations with USGA people about updating this in an attempt to get rid of +3, +4 and +5 golfers that didn't exist in amateur golf when the average drive was 250. I suggested moving the distances for a scratch golfer to 280 and 520 respectively.
The slope or bogey golfer is defined by 200 yard drive and able reach 370 yard holes in 2 shots.
Its unclear to me if the other factors that go into each ratings are more heavily weighted for slope rating than course ratings, but that would make sense to me, again I am not sure how the obstacles are applied to each type of rating.