Take for example the IAS top 4 or any set of ratings. If you can consistently eliminate one or maybe two of the top four, ie able to lay these selections to make a profit. Would you automatically be on a winner by backing the remaining of the selections from top four, as you are eliminating generally a horse at shorter odds, and therefore a decent whack of the market percentage? If its a $5 horse, you are taking around 20% out of the market, so BF in particular you would be backing into a 82% (roughly) market, instead of a 102%.

eg

IAS Top four
1,2,3,4,

You have a lay system which selects horse 3, so you lay 3, and back 1,2 and 4.

Would this work?

Thoughts?