February 05, 2019

Machine Learning the Crew

February 05, 2019/ Eliot McKinley

Machine learning is so hot right now and if Skynet is going to destroy all humans, it should at least know a little bit about Major League Soccer’s Columbus Crew. To wit, I created a machine learning model to classify which position in a Gregg Berhalter 4-2-3-1 formation a player most likely played in during a single game.

I chose the Crew for a couple reasons. First, they are my favorite team. Second, they had consistent coaching for a long period of time with a defined style of play. The latter is very important, as the model has to be trained well in order for the results to make sense. Since the Crew almost always played a 4-2-3-1 that relied on ball possession to disorganize the defense and create goal opportunities (get used to that phrase USMNT fans) it was a perfect test of whether this kind of thing could be done.

January 31, 2019

Interactive Tables Update

January 31, 2019/ Matthias Kullowatz

We recently updated the app with a few more bells and whistles so that you can make more noise. I explained the xGoal model changes earlier(link), so here I’ll highlight the app’s key updates. We’ve made the app accessible publicly, we’ve integrated compensation into the data tabs, and we’ve improved sidebar filter options.

January 28, 2019

Model Update: Coefficient Blending

January 28, 2019/ Matthias Kullowatz

With our most recent app update, you might notice that some numbers in the xGoals tables have changed for past years where it wouldn’t normally make sense to see changes. As an example, Josef Martinez had 29.2 xG in 2018, but updated app shows 28.7 (-1.7%). No, this is not an Atlanta effect, though I can understand why you might support such an effect. Gyasi Zardes lost 0.5 xG as well (-2.4%), and no one dislikes Columbus.

We have updated our xGoal models with the 2018 season’s data, and that is the culprit of all the discrepancies since the last version of the app. I have already cited the largest two discrepancies by magnitude, so this isn’t some major overhaul of the model. In fact, only 2018’s xG values have been materially adjusted.* The new model estimated 35.6 fewer xGoals in 2018 than it did before, equivalent to a 2.8% drop.

January 25, 2019

How to find Transfer Market Success in MLS

January 25, 2019/ Benjamin Bellman

Analyzing Foreign Transfers to MLS with Survival Analysis

Finding success in the global transfer market is a critical part of a winning MLS season. While the U.S. is obviously progressing as a soccer nation, there just aren’t enough talented players from this country to satisfy its growing thirst for exciting play and trophies. Still, signing players that are unfamiliar with MLS has also been a risky prospect. Foreign signings with poor outcomes can waste valuable international roster spots, and destroy a team’s budget in a relatively low-spending league. However, Atlanta United and LAFC have shown that signing players who can contribute immediately can make an expansion team an immediate contender. Understanding the historical structural patterns in the success and failure of past MLS teams could offer insights into navigating these decisions, for both future teams and those who need players for 2019 and beyond. Obviously, the most important considerations for signing a player have to do with style of play and personality, but understanding general hotspots and mistakes could improve the odds of signing foreign players who succeed in MLS.

January 23, 2019

A Tale of Two Central Defensive Midfielders

January 23, 2019/ Eliot McKinley

Michael Bradley and Wil Trapp share several obvious qualities. They are both captains for club and country. They are both smooth passing defensive midfielders, and they both possess excellent heads of hair. Another similarity is that they rarely shoot or score goals, each collecting only one goal over the last three seasons. Coincidentally, both of those goals are what we could enthusiastically describe as "wonder-goals." Bradley's long-distance chip for the US national team in a World Cup qualifier against Mexico at the Azteca (a goal not remembered as fondly as it deserves due to the rest of qualifying) and Trapp for the Crew to win a match in stoppage time against Orlando City this past summer. However, one difference between these two players was how each responded to the confidence boost that came after scoring a once-in-a-career goal.

January 22, 2019

Going to WAR for Points Above Replacement in Soccer

January 22, 2019/ Dave Laidig

Baseball popularized the use of the Wins Above Replacement (WAR) statistic; representing a player’s estimated contribution to a team’s win tally above what a generic replacement would contribute. In this sense, it’s a roster management tool to support a keep/replace decision. However, WAR stats are often used by others for general performance comparisons. But soccer (or football if you like) does not have widespread use of a WAR-like statistic.

In soccer, performance indices are typically confidential and proprietary, making it difficult to verify their validity. Teams and analysts, understandably so, do not want to give away their competitive advantage. And those that are shared publicly, do not usually describe values in terms of team performance, or comparisons to replacements.

January 14, 2019

Turf and Injuries: The Data Hurts

January 14, 2019/ DMP

One of the most peculiar matches of the 2018 regular season occurred on August 18th. The LA Galaxy were already stretched thin from injuries to both dos Santos-es and Romain Alessandrini (their three DPs) and defender Michael Ciani for Sigi Schmid’s return to Seattle. But when they showed up in town, there was a huge name - perhaps the biggest name in MLS - missing from the lineup. That name was Zlatan, and by all indication his absence was voluntary.

By the end of the afternoon, the Galaxy really could have used one of the greatest players ever to kick a soccer ball. They ended up suffering their worst loss of the season and Seattle notched their best (5-0). Oh yeah, and the Galaxy missed the playoffs by less than three points.

We all know why he missed that game. It’s because the Sounders play on FieldTurf. There’s a perception out there that playing on artificial grass increases the risk of injury, and Zlatan had hurt his knee not long before (not on turf).

The superstar is not alone in his perception. I remember being disappointed not to see Thierry Henry play at CenturyLink Field in 2013. In fact, a group of Canadian researchers surveyed 99 MLS players back in 2011 and found that the vast majority (93%) said they believe third-generation artificial turf (FieldTurf) increases the risk of injury.

January 09, 2019

Ranking MLS' Best Foreign Goalkeepers

January 09, 2019/ Bill Reno

It’s hard not to have a love-hate relationship with the MLS offseason. On one hand, we get to talk about goalkeepers more often. (A massive plus for anyone.) Typically the narrative wraps up a year-long performance in one or two sentences - “Goalkeeper X will look to build off of last year’s success by relying on his shot stopping and distribution skills.” - but that’s hardly a problem considering the larger headache that resurfaces this time of year. Every January we hear about an unnamed MLS team being linked to a foreign goalkeeper. We just had one happen last week, with a “lucrative offer” apparently on the table for a German goalkeeper.

January 07, 2019

Player Value Recap 2018: Refining a System for Ranking MLS Players

January 07, 2019/ Dave Laidig

Creating an all-encompassing player value metric is an ongoing process, with more data adding more insight and texture to its meaning. But the challenges are worthwhile. The ability to compare players from different positions on equal footing, like PER for the NBA or WAR for MLB, allows one to test assumptions for what makes a team successful, how players fit together, and where resources might best be spent. If you haven’t already, read my pieces from last year (here are parts one and two). But this is an update on my progress to creating a metric to describe how game actions affect game outcomes, based on the context of team possessions.

January 02, 2019

Why the new MLS Playoff format doesn't create a more meaningful regular season

January 02, 2019/ Jared Young

Major League Soccer has updated their playoff format for 2019 to a March Madness style single elimination tournament that will take roughly a month play out. The prior competition used a combination of single elimination and home and away ties over a month and a half period, and had long breaks in the action. The one clear benefit of this change is the shortened duration of the tournament. Avoiding the November international window will create a compact and uninterrupted tournament that should improve the momentum of the story lines that emerge.

The new format is also supposed to benefit the higher seeds, as the single elimination games will give advantage to the home teams, versus the old method of home and away legs for each team. This seemingly makes regular season games more important. More Victory! [Insert scratching record sound here]. These types of simplifying statements make my geek antenna start to hone in on theoretical galaxies of mathematics. Sadly, the only off switch I have for my antenna is my keypad and a Google docs session. So let’s dig in and deconstruct this new tournament bracket and see who benefits and who does not.

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