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How Much Does Luck Affect MLS?


Following my recent article for Betting Expert quantifying how large a role luck plays in the English Premier League (EPL) I thought it would be interesting to look at Major League Soccer (MLS) too.

MLS Structure

MLS is structured differently to the EPL as it has followed other North American sports in implementing wage caps and player drafts. Unlike the current salary free-for-all in the EPL, MLS clubs are currently limited to spending a maximum of $2.95 million in wages over their first 20 roster spots, with up to three additional designated players paid (partially) outside of this salary cap.

MLS also has a draft system that takes place each January during which teams can sign players graduating from college or otherwise signed by the league. The draft is split into three rounds and is designed to give priority to the league’s weaker teams allowing them first choice of players ahead of the more successful teams.

MLS is also a shorter season than the EPL with teams playing just 34 matches compared with the EPL’s 38. This is important as the more matches that are played then the more opportunity talent has to overcome luck.

Overall, this all works towards increasing parity in the MLS and making it a more evenly balanced league, which in turn should enhance the role luck plays.


Using my adaptation of Tom ‘Tango’ Tiger’s baseball equation I calculated the average win rate in MLS going back to 2004 and the variance of the win rate. I them calculated the variance expected due to luck and subtracted one from the other to get the amount of variance attributed to talent.

Luck accounts for around 35% of a team’s win rate in the EPL and I was expecting MLS to be higher, but it initially came out at a staggering 82% for MLS. Instinctively this seems too high and I suspect it is inaccurate due to the changes in MLS’s structure over the years. For example, back in 2004 there were only ten teams and one conference while there are currently 19 teams and two conferences. There have also been changes to the level of the salary cap and the number of designated players allowed over this time period too.

So I went back and reprocessed the results using just the 2010–2012 data. Although this reduces the sample size considerably it leaves us with data more representative of the current state of MLS. And the results this time? Luck accounted for around 57% of a team’s win percentage compared with just 43% for talent.

So compared with the EPL, the structure of MLS does appear to increase parity and enhance the influence luck has in deciding the league champions. In fact, being lucky is probably the more important of the two, although luck on its own is not enough – you need to be a talented team with luck on its side to win the MLS Cup.


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