We have been told that the Betfair market is very accurate, but maybe Maria indicated that it may not necessarily be so?

She did no calculations to determine a price on any of her selections so she would not have been aware if she was getting unders or overs. If the market was accurate then there is every possibility that half of her bets would have been on overs and the other half of her bets would be on unders. As she had so many bets it could be assumed that the overs and the unders would more or less even themselves out - the swings and roundabouts syndrome.

It appears she achieved her huge profit from a somewhat mechanical system, which would indicate that the market may not be entirely accurate particularly for horses whose Betfair price is under $11.00?

As an aside, if she could make a profit from laying horses under $11 then one could wonder if she, using opposite criteria could then make a profit by backing horses over $11?

Just a thought...