Did a little data exercise to see how good the pregame market has been to nail the correct probability for home/draws/away wins. The data consist of 91515 soccer matches played in 2014,2015 and 2016.
I calculated the implied probabilities from the pregame odds (1/odds), and distributed the over-round evenly over the three scenarios. Then I summed them together with the actual wins.
This first table shows that the market hade the most problems with the Away predictions. Market predicted the Away teams to win corresponding to 29027 times, but they actually only won 28192 times (which is a diff of 2.9%).
I dug a little deeper to see how the situation is when dividing by pregame favorite:
Now I start to identify some areas which the market seems to have bigger problems with... such as the probability for an Away win when the pregame favorite is a Home win.
This could be a starting point when designing a new strategy. Find a nische where the market has problems, and try to be the best in that nische :) Now I will continue to mine my data, and see if I can find a new nische area.