Rewriting History

I was a little surprised to see that Odds Portal has Coventry City as favourites for the Championship playoff game later this month, since every individual book I'd looked at has Luton Town as market leaders, but when I drilled down it turns out that the nominal Home team is actually Coventry, not Luton as appears to be the case (see above).

I also noticed that some of the historical prices on this site change in time. My practice is to update my spreadsheets fairly soon after the match is over and once the fixture moves into the results page, with the assumption that these numbers were now set in stone, but as with many assumptions, this one appears to be wrong. 

My guess is that the sportsbooks used change over time, and that when one is dropped, not only are their odds not available moving forward, but their odds on historic games are also erased, which can possibly result in changes to the Average and Highest Prices. 

Not the biggest concern in the world, but I like any numbers I show on this blog to be verifiable as I have noted before, but this may not always be the case. And no, I don't have time to go back and confirm 2600 entries! 

With that in mind, here are the odds and results for the Championship playoff game since records began:

As with all the playoff data, the sample size is small, but backing the favourite has been the profitable strategy over the years with an ROI of 34% from the 19 matches. Given that this game is a Final, it's surprising how few Draws there have been with just three since 2004 and just four in the first 14 for which I have no price data. 

The data for the League One and League Two playoff finals is similar, with an ROI from backing the Draw of -13% and a 3% edge when backing the favourite, none of which have ever been priced at (fair priced) odds-on. 

Illustrative of the problem with small sample sizes is that prior to this week's Champions League Semi-Final Second Leg matches, the edge on backing the Home team was 6% and for the Draw was 10%. After two Home wins, the ROIs are now 11% and 4% respectively, but laying the Away team or the 3rd favourite continues to be a solid strategy with ROIs of 7% and 14% respectively.

In the Europa League and Europa Conference League, the story is similar with Away teams and 3rd favourite outcomes to be opposed. Just 5 of 38 Away teams have won (and in four of those they had a 2+ goal lead from the first leg) and just four 3rd favourites. ROIs on these two strategies are 18% and 12% respectively, but again, small samples.