Thanks CP for your input. It is always appreciated.
Thinking out loud here, more to invoke discussion. We have to get better ratings. We need them to beat the market movements. The tote runs on pure weight of money and the end result is consistent with the true odds of the horse if the rake was added back, so long term you lose what the TAB grabs. This is similar with the bookies and the exchanges. So you have to be better and/ or be good at cherrypicking.
There are hundreds of ratings out there. The majority don't go near beating the openers. They all start with the history and put specific weighting on each impact value. Within a range they all produce a similar result.

When the trainer nominates he is expecting an even field. When the handicapper finishes he is certain that within his guidelines he has created an even field. Everybody else knows different.

Now Mark R has been rating for eons and at most venues and all races. To do so he must utilize a formula. He can't study and formulate that amount of races in that time. So he has to have help and a formula for consistency.

So the bottom line is "What impact values does he rate highest and most relevant? Then his second etc."