James -
Good question and keen observation.
Actually the system is working as intended.
Here's the reasoning:
Points allocated are based on the number of riders starting. As the fields grow, the total volume of points given out increases much faster. ie. - when the field size doubles, the volume of points given out (sum of all points) quadruples.
So to keep the system in check, so consistant top finishers have the best advantage to stay in contention, as field sizes grow, the percetage of the field earning points decreases.
The limits set right now are:
less than 35 starters - 66% of the field earns 'some' points
35-49 starters - 60% of the field earns points
50 or more starters - 50% of the field earns points
So for you're situation, the field size was just over the limit cutting back the number of riders scoring points to 50% and eliminating a few positions scoring point. Again - this is per design so the advantage remains with the top finishers while still rewarding riders for finishing average to well.
Once we see the occasional field size over 70 or so, we'll probably add another higher limit to keep the advantage on the top finishers. We can only hope for that we'll be forced to make this change in the near future.
Let me know if you have any more questions on this.
Jeremy