Opta Expected Goals

How often football commentators say something along the lines "striker has to score from here", "it was an easy stop for goalkeeper" or "it was an excellent opportunity"? How many times have you cursed, because your favorite team missed an obvious chance to take the lead? In a tense game, both we (the fans) and the commentators tend to give the way to emotions and leave rational thinking on the bench. Yet with the modern technology and understanding of statistics it is quite possible to calculate odds of scoring a goal in a particular situation.

Watch this video by Opta in which their metric "expected goals" is explained. Though it is not very detailed explanation, but it could spark your own imagination.