Expected Goal Chains

Our Favorite ASA Articles of 2018 by Drew Olsen

During a recent American Soccer Analysis shareholders meeting in the penthouse suite of the swanky hotel we built in Minecraft (it’s our Slack channel), we discussed our favorite ASA articles of the past year. Because it is the season of listicles and we relish every chance to talk about ourselves, we decided to put them all together in one official post. Also, our site traffic is essentially zero at this time of year, so it seemed like an easy way for us to remember where we put them.

It was a great year for MLS (though perhaps not American soccer overall) and the most successful in our five year life as a website. We added interactive tables, introduced xPG, rebooted the podcast (new episode coming out soon! …probably), and added a lot of great new writers to our existing ranks of stale old writers. They’re not all represented in the list below, but special shout out to our weekly contributors who put together content every week - Little Things (@harrisonhamm21), Lowered Expectations (@harrison_crow), Expected Narratives (@ahandleforian), and Setting the Table (@ericwsoccer) - showed us the individual plays each week that made up the whole of the MLS season. We’d also like to extend a special thank you to Neil Greenberg of the Washington Post, for including us as a part of the WaPo’s incredible World Cup coverage.

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Expected Goal Chains: The Link between Passing Sequences and Shots by Kevin Shank

For those who are not familiar with Expected Goal Chains (xGC), the metric looks at all passing sequences that lead to a shot and credits each player involved with the xG. Instead of just looking at expected goals and expected assists, which primarily benefits strikers and attacking midfielders, xG Chains is beneficial to every player involved in a sequence. Most importantly xGC credits those defensive or two-way players who are integral to a play’s build-up but don’t necessarily serve that final key pass. To calculate xGC, I assembled every pass, shot, foul, and defensive action so far in MLS and assigned a unique ID to each passing sequence. When a sequence ended in a shot, each player is attributed with the xG from that shot. StatsBomb defines it very succinctly, so the below steps are stolen directly from them: 

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