The system is based on predicting the draw. I have reasoned that, if two teams are evenly matched then there is a greater chance of there being a draw. The way to spot this is simple. Just look at the Asian Handicap. A +0 handicap implies there's not much between the teams.

I've done the maths based on data from www.football-data.co.uk on the English Premiership. Betting on the draw (at the best bookie odds) when the Asian Handicap is +0 (at Bet365) would have produced a yield of 4% last season and 7.5% the season before. I would go back further but the data before doesn't contain Asian Handicap information.