I don't know what happened to him at the Belmont, but there is one possible theory. Before the race the commentary was made that Big Brown had been getting a legal shot of steroids once a month. The owner stated that he wanted everyone to see that he could win the race without the shot. This is his first race without the shot, perhaps this might have affected his performance. Just a theory. However, the temperature was a steamy 93 degrees, I can't imagine running a mile and half in that kind of heat. He was also fitted with a new pair of custom glue-on shoes, don't know how much affect this could have had on his surefootedness.