American Soccer Analysis on Monday announced the creation of a new metric by which to judge players' contributions to a game, known simply as "goals added."
Essentially, the metric takes data from every single on-the-ball action during a game, and measures how each action by each player changes the team's probability of scoring or conceding a goal during that sequence of play.
The metric does not factor in whether or not a player actually contributes a goal or an assist during his action — rather only if he increases his team's probability of scoring. But even without factoring in goals and assists, a 2019 MLS best XI based on those metrics reveals a lineup similar to what a panel of expert journalists might choose, with the obvious choices of Zlatan Ibrahimovic and Carlos Vela leading the way. (Josef Martinez was not in the XI because he was competing with Ibrahimovic directly for the No. 9 role).
There are still limitations to this metric, of course, most notably that it doesn't quantify the impact of off-the-ball play. That is something that MLS partner Spectrum Sports is trying to do with its own player tracking technology. And off-the-ball movements are often just as important in the overall flow of the game, be they matters of defensive spacing or making runs offensively that clear space for others.
For example, MLS teammates have raved about the defensive positioning abilities of star strikers recent past like David Villa and Wayne Rooney, even if their on-the-ball actions on the defensive side were relatively rare. ("The Tackle" not withstanding.)
American Soccer Analysis will be publishing more content around its new metric all week, so be sure to check back.
