Let's say in Don Chendo race, the public has made it top elect , not because of the post position, but because of Time, and Early speed. Your handicapping may decide it is 2nd elect. When the race has been run, they were right you were wrong, now you record this over and over for every race that matches that same situation you find your a loser on those types of matching races, now you know you have a "blind spot" in your handicapping for this subset.
Either you avoid those races or wager differently and become a winner.