Admittedly, I did forget that the 10k events are coming back, so perhaps the average field size will get smaller. But I can't imagine it will be by a huge amount.
EDIT: Corrected. You're right, it's not the best way of looking at it. Perhaps I should estimate the field sizes of the small events, calc the chances of winning those events, and add that probability to that of winning the larger field events.
EDIT 2: Then again, we can't exactly estimate his edge as being massive against those pro-heavy fields. That first probability is probably in the neighborhood of 10%.