Arsenal v Man Utd - 1st Booking Market

1st Booking is a market tha bookmakers struggle to get right. I'm not sure why as the statistics for this are all widely availible.

I'm placing 2pts on Ronaldo (18-1) and 2pts on Van Nistlerooy (18-1), both for 1st Booking at Paddy Power. Both of these players should be approximately 10-1 (which they are at other bookmakers) as they have some of the highest card/game ratios.