JB,
First,as you know, horses do not go bad ONLY because of how frequently they race as 2 yr olds.Young horses go bad many more times over working, galloping, jogging or breezing than they do racing. Of course, they \'work/exercise every day\' race less frequently.A fair number go bad before they even start.
ALL modern horses are ticking time bombs,imo, whether you baby them or drill them.Don\'t know offhand about your question but do know that the level of caution exercised today with 2 yr olds by trainers vs what happened 10+ years back is night and day.
Old man Woody rolling in his grave but he dealt with much more sound animals.
Mike