Published at SB Nation.
It isn’t precisely true that no one expected Liverpool to be title contenders. A number of statistical models viewed Liverpool as one of the best sides in the EPL last year. My expected goals ratio, a ratio of expected goals scored to expected goals allowed based on chance quality, rated Liverpool as the league’s best side last season.
The method behind expected goals, which you can read about in the “Shot Matrix” articles linked above or at the EPL Advanced Stats page, is pretty simple. For each chance, I estimate the average probability of a goal being scored, based on location on the pitch, whether the shot is taken with the head or the foot, whether it is a free kick or from open play, and the type of pass that assisted the shot. Over time, these estimates of chance quality are a better metric of team quality than raw goals scored or simple shot totals. And in the case of Liverpool, based on their expected goals in 2012-2013, the underlying stats expected this club to be among the best in the Premier League.