I'm not really sure what knowledge can be gained from the stats on there to be honest. I just had a look at the analysis on backing the favourites, it seems to imply that backing the favourite is not a good strategy since it has returned a loss over thousands of races. What he doesn't mention is how many of them favourites had value in them, betting on any horses at any odds will return a loss in the long run if there isn't a positive expectation from the bet.
I think it depends on your goal, betting on the favourite has some advantages, there are lot of them so you can get a decent amount of bets on, they also win often enough that you don't lose faith in your strategy. My goal is to ger as many bets on as possible.
On a single point basis you might make more backing an outsider, but you will hit very long losing streaks so you need a good bank roll to support it. If you are using some kind of proportional staking system then it will be harder to recover after the long streak too.