Dr Ron

No stats for you, but, more winners than losers open shorter than their newspaper price (I use Friday's Courier Mail)
eg there might be 8 races with a total of 96 runners, I would expect that 48 runners open at the same price or longer (get rid of these) & of the rest, they average 6 winners. This is only a generalisation as I have not studied it in great detail, but I have seen fields of 14 runners where there are only 3 that open shorter & they've run 1-2-3.
Just as a trial, go through the results on Sunday, crossing out those that open the same or longer, and see how it goes. If I remember I'll post results.