Welcome to the forum. I’m not sure what you mean here. The short answer is that no horse would be raised in the handicap unless it showed improved form.<br>If jockeys give horses a good/bad ride, it will affect the horse’s finishing position(and hence the finishing position of all other horses) and subsequent rating.
If you are keen to find out about handicapping or horse racing, there are several good books available quite cheaply such as the Channel 4 guide.
frankanwin if you win by 12 lengths you are going to be punished by the handicapper. You could have done with running in a decent handicap while you were well in. Hopefully you will have listed and group races to look forward to instead.