On May 7, 2019, Liverpool played Barcelona with a slim (most people thought nil) chance to make the Champions League Final. Having lost previously to Barcelona 3-0, Liverpool needed to win the match by at least four goals to advance. Amazingly, Liverpool won the match 4-0 and then went on to defeat Tottenham 2-0 in the Champions League Final. In this chapter, we will place this great upset in proper perspective relative to other great sports upsets.
How Should We Rank Upsets?
Let's rank upsets by the chance of the upset occurring. For each sporting event, we could try to build a sophisticated math model to predict the likelihood of the upset happening, but the bookmakers have done the work for us. Betting markets estimate the probability of an event happening. As we will see in Chapter 23 “How well does Vegas predict the outcome of sporting events?” betting markets usually create unbiased forecasts. For example, if the oddsmakers declare a team has a 90% chance to win a game, then on average, these 90% favorites win 90% of the time.
The odds on Liverpool advancing past Barcelona were 18-1 (
www.fanduel.com/theduel/posts/liverpool-s-odds-to-advance-to-champions-league-final-over-fc-barcelona-were-astronomical-01daa13vzxn8). To understand how this implies a probability that Liverpool would advance, let's assume for the moment (we will later relax this assumption) that the oddsmakers set “fair odds” that ...