Out of interest I looked at:

1) Fields of 10-plus runners,
2) Finished 7th or worse at last start.

Yesterday there were 101 selections from 24 qualifying races for 7 winners. If they were bet on Unitab for $1.00 then the return would have been $155.10 for a profit of $54.10. However, if they were bet (hypothetically) on Betfair for $1.00 on the exchange the return (includes 6.5% takeout) would have been $264.00 for a profit of $163 - approximately three times TAB's profit.

I know yesterday was a bad day on the Lay Outsiders method with 3 accidents which have flattered the above results, but there would have been another four winners.

I'ts something I might look at if/when I get time.