Building a System for Assessing Player Value

Building a System for Assessing Player Value

For years I’ve been interested in how players contribute to team results.  I’ve sought a measure of player contributions to a win that covered all aspects of a game. While many valuable and informative soccer metrics have been created, common stats are not entirely on point with this issue.

For example, xG stats apply only to scoring attempts, and perhaps goalkeepers. Adding xAssists and key passes broadens the scope of included players. But the contribution of defensive oriented players would not be expected to show up on these metrics. And offensive-oriented players would still rely on teammates to threaten the net before their effort can be measured.

The xGChain metric is useful for identifying players that participate in the most productive attacks, and includes players that play further away from the goal. But this metric does not include non-offensive actions. And each players’ contribution is given equal weight, whether it’s the initial square pass to a CB in the defensive half, or delivering a cross into the penalty area. Experienced analysts consider the dashboard of key performance indicators and piece together insights from the elements.  But I’m looking to consolidate all game elements with a common perspective.

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Expected Narratives: Seattle Can't/Won't Stop; Presumably Sorry/Not Sorry

Expected Narratives: Seattle Can't/Won't Stop; Presumably Sorry/Not Sorry

Wayne Rooney has conquered Major League Soccer. It is time to forget all of that clearly misguided “young South American talent Atlanta-y whatever” and get back to what really works and that’s bringing in over 30 stars from European leagues. I chuckle heartily at all of you “it’s not his age, it’s how many minutes he’s played - the man can barely run” types who seem somewhat surprised to watch the captain and leading goalscorer of England and Manchester United perform at a high level in Major League Soccer. I mean he’s turned Luciano Acosta into Ronaldo (either one, take your pick - I don’t care), and vanquished the mighty outliers of Atlanta.  All hyperbole aside, DC United are looking good and that’s something worth smiling about.

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Lowered Expectations: Week 27

Lowered Expectations: Week 27

Welcome to Lowered Expectations, week 27 edition! Each week, we go about posting chalkboards and GIFs of the weekend’s best open-play shot attempts which did not quite live up to expectations (and rarely do we update this paragraph). We look at each one and not only evaluate the results, but also the process leading to them.

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The case for pulling the goalie in soccer and the math behind Ben Olsen's madness

The case for pulling the goalie in soccer and the math behind Ben Olsen's madness

The game is ice hockey. One team is behind a goal as the seconds wind down. Conventional thinking for the head coach of the losing team is to direct the goalie off the ice while a substitute enters the game. This gives the team a six to five player advantage at one end of the ice, but gives the leading team a much higher chance of adding to their lead. Starting in 2013 NHL teams became more aggressive with this strategy, and a paper released earlier this year proposed that teams should get at least three times as aggressive as they are. The math clearly lines up with the strategy.

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Lowered Expectations: Week 26

Lowered Expectations: Week 26

Welcome to Lowered Expectations, week 25 edition! Each week, we go about posting chalkboards and GIFs of the weekend’s best open-play shot attempts which did not quite live up to expectations (and rarely do we update this paragraph). We look at each one and not only evaluate the results, but also the process leading to them.

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Expected Narratives: Chara's MVP Chances and Dempsey's Place In History

Expected Narratives: Chara's MVP Chances and Dempsey's Place In History

Ok fine. Nothing Josef Martinez has or will do is within the jurisdiction of analysis. He is perfect in every way. He has created 28 goals from nothing. Where once there were scoreless games Josef declared “let there be goals” and he saw the goals and he saw that they were good. I cannot see how Atlanta fans will take issue with this, so I can’t wait to see the ways in which they will. I’m going to say something nice about Philadelphia now, because I’m jealous that other soccer writing people get their pull quotes immortalized in the awesome brushtip font on Twitter. So here we go:

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The Next Level of xG: Expected Possession Goals

The Next Level of xG: Expected Possession Goals

Using xPG variants to assess risk-and-reward of the game

We introduced Expected Possession Goals (xPG) in two recent articles. xPG groups and rates the outcome of a possession and began from an idea that every action in the possession connects to create a shot. Here, we’re introducing new xPG variants, extensions to the original xPG definition to assess the risks and rewards inherent in a soccer possession.

xPG rates a group of uninterrupted events - or when an interruption lasts fewer than two seconds - based on where the ball travels. It assumes the purpose of the possession is to move the ball within shooting distance.

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The Legend of Josef Martinez and what it takes to get to 27 (and more) goals

The Legend of Josef Martinez and what it takes to get to 27 (and more) goals

Josef Martinez is a man on fire, and, as of writing this, he currently sits on 28 goals in 2018, having just broken the all time scoring record of 27 first set by Roy Lassiter in MLS’ inaugural season and matched by Chris Wondolowski in 2012 and Bradley Wright Phillips in 2014.

But I want to take this opportunity to look at how goal scorers score goals, and compare Wondolowski, Bradley Wright-Phillips and Martinez (we don’t have data on Lassiter, sadly) on their march to 27. Yes, Martinez has broken the record, but this article is going to deal with his stats on the way to 27. For a more complete breakdown of his data and where he lands, I’m sure someone at ASA (let’s say, Harrison) will write you that article at the end of the year.

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Expected Narratives: Wazza Saves DC and Josef Martinez is not an Elite Finisher

Expected Narratives: Wazza Saves DC and Josef Martinez is not an Elite Finisher

Ah, Rivalry Week sponsored by Heineken. Who doesn’t want to ride for this twice annual celebration of American soccer’s most storied rivalries and also some ones that MLS just went and made up? Frankly speaking, rivalry week can kiss m-(Editor’s note: I redacted like a whole paragraph here, you’re welcome. Also, Heineken is gross.) - because Atlanta and Orlando are not a real rivalry just because some marketing executive bought a billboar-(Editor’s note: yeah some more here as well) ight- and even if these ARE the most exciting rivalries in the league why not spread those out so you can have a compelling match every couple of weeks? I don’t know folks. I hate rivalry week. It makes the fans extra ultzy, it sort of cheapens the real rivalries, and all these kids will simply not get off of my lawn. Is it mainly because I never spell Heineken right? Mainly. Yes. Whatever.

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