First of all, synthetic surfaces are here to stay. The tragedy of Eight Belles has forced the racing industry to make sure that another incident like that ever happens again, particularly during the sport's major events. The only question was which type of synthetic and how to take maintain it.
Curlin may have lost in part because the Pro-Ride surface, but the fact that not one horse was pulled up, pulled out, or broke down during the two days of Breeder's Cup race is a huge deal. Yesterday was a particularly hot day, a day that normally leads to injuries. There were none. So, between having a dual Breeder's Cup Classic Winner on side and an injury free day, I will take the injury free day.
Now, having said that, Curlin lost to the better horse. Yes he may not have "liked" the Pro-ride, but consider that the Europeans travelled thousands of miles which is often go against horses. European horses don't ride on pro-ride. They ride on grass.
Lastly, it was a good field of horses, the best field of Curlin ever faced. There is no shame that he lost. But there are no excuses either. Curlin ran because his owner and trainer thought he was one of the best of all time. Secretariat won on the grass, twice. The race showed that Curin is a very very good race horse, but not one of the best ever.