this is the last bastion used by trainers as to why a horse wont win. many times, owners refuse to deal with the reality of their pride and joy. the fact that their horse doesn't have the ability and/or desire to win is simply beyond them.
I don't feel as there is that much difference in a horses level of performance before or after they are gelded.
there was a book written entitled 1,000 excuses trainers use for a horse losing a race.
it may have just been the timing of the conversation one night, but I remember an owner in despair desperately seeking a reason from walter paisley who had just driven the owners horse that had made a break while racing. "why....why did he make that break?" butch, who was known to pull no punches at times told the owner, simply, "because that was easier than going fast".