Originally, the A group contained the best golfers or those golfers most likely to win and of course make the cut. B was to have golfers not as good as the A-Group and then C-Group would have PGA players with the worst performance or least chance to win and most or all rookies.
This has not been followed closely in recent years. The 2,4,2 wrinkle does have some effect on Fantasy Play. If both your A players make the cut and only one B-player, the A, B, C Groups changes play as compared one Group of 8 golfers with any 4 allowed to fill roster slots.
A, B, C is a wrinkle - the Grouping basis does not have the same criteria that were once used or at best it is followed with less rigor.