Kentucky Derby.

Big Brown's winning margin was 3 1/2 lengths, according to this piece.

Legitimate questions can be raised about soundness issues in thoroughbreds. There are far too many injuries on the racetrack, unlike decades ago. Back then, horses like Exterminator and Whirlaway could run dozens of races and never have problems. I think a lot of breeders want speed rather than soundness, and this is detrimental to the breed.

Here is a sane point of view.