ASA Series on Caponomics, Part one: Introduction and Goalkeeping Application / by Tom Worville

This is part one of a four-part series examining market inefficiency in Major League Soccer. The portions on defenders, midfielders, and forwards will be published on Fridays for the next three weeks.

By Tom Worville (@worville)

In this series of articles I’m going to explore further my OPTA Pro conference submission, which can be read here. The data I’m going to be using is not going to be as in depth as suggested in that submission. Instead I’m going to Whoscored ratings (thanks to @JaredEYoung for pointing me to this article) and MLS salary data taken from the MLS Players Union here. For an explanation of how Whoscored ratings work, click here.

The aim of my presentation is to display how the market for players is inefficient. In MLS, looking at players who have more than 10 appearances (starts and substitutions) and including players from all teams, the correlation between a player's Whoscored Rating and their salary is 0.25.

This indicates a low correlation between the salary a player is paid and how well he performs; i.e. paying a player a huge salary doesn’t mean you’re going to get a low performance level and vice versa. The market inefficiency shown through this means there are gains to be made when looking for player performance (which is what you are trying to get the most of in a team).

Obviously soccer is a team game, and this article is looking at player performance from an individual point of view. It is important to note that at this time, it’s difficult to quantify team chemistry with analytics, which is an important part of football. Purely looking at player performance also discounts the off-field and intangible aspects of signing a player: leadership, revenue generation through merchandising and ticket sales, coaching commitments, club loyalty, manager-player relationships, work rate, etc.

Evidently, given the data on this it would paint a picture of which players are signed for what reasons and allow us to allocate a specific amount of money toward each specific reason. For example, you could break down the salary of Thierry Henry into his marketability, performances on the pitch, influence on other players in training and so on. Sadly, the data is not available, and I doubt as an outside analyst (by this I mean someone not working within a club) I will never have access to this kind of information.

But even without that data, analysis can focus primarily on the performance of a player vs his salary. I've broken down the players into four distinct baskets focusing on the position that they play in: Goalkeeper (GK), Defender (D), Midfielder (M), and Forward (F). The average wages and ratings for those are given below:

Position Average WS RatingMedian Salary
GK 6.75 $132,478.56
D 6.94 $152,419.91
M 6.75 $207,338.24
F 6.77 $221,506.11

Note: Median wages used due to the top wages for DP’s skewing the average significantly.

Forwards are typically the highest paid players in the league, with goalkeepers being the lowest paid. This makes sense in the current footballing climate - the more flashy, attacking players are valued higher (and therefore paid more) than their more defensive team mates. This does mean that a great goalkeeper is likely to cost less than a decent striker but is as, if not more, integral to the team.

The Numbers Game famously highlights inefficiencies in the transfer market. One of the chapters within the book concludes that a clean sheet is more valuable for a team than scoring a goal. At the end of the day this is football 101 - you start with a point at 0-0 and you can either try and preserve that point or attack and try and score more than your opponent to get all 3 points.

In this series of four articles I’m going to show my findings for each of the four positions, starting with the goalkeeper. The sortable table below shows the salary of all 22 goalkeepers that had more than 10 appearances in 2014, sorted by their Whoscored Rating (WS Rating). The correlation between WS Rating and Salary for goalkeepers specifically was actually negative in 2014, indicating a potentially greater inefficiency in the goalkeeping market. 

Name 2014 Team WS Rating Salary
Bill Hamid DCU7.12 $114,750
Jeff Attinella RSL7.11 $48,825
Andy Gruenebaum SKC 6.94 $85,000
Steve Clark CLB6.91 $138,333
Jon Busch SJ6.9 $184,583
Jaime Penedo LA 6.87 $138,562
Nick Rimando RSL6.86 $235,833
Bobby Shuttleworth NE 6.79 $100,000
Chris Seitz FCD6.78 $105,000
Donovan Ricketts POR 6.77 $260,000
David Ousted VAN 6.76 $266,156
Raul Fernandez FCD6.74 $247,500
Luis Robles NYRB 6.73 $125,000
Troy Perkins MTL6.69 $271,833
Sean Johnson CHI6.69 $253,000
Stefan Frei SEA 6.66 $150,000
Clint Irwin COL6.62 $87,000
Joe Bendik TFC 6.61 $147,375
Zac MacMath COL6.59 $51,325
Eric Kronberg SKC 6.58 $120,000
Tyler Deric HOU6.58 $97,667
Evan Bush MTL 6.49 $48,825
Tally Hall HOU 6.37 $213,500
Dan Kennedy CHV 6.33 $213,417

As stated previously, goalkeepers are the least valued players in the league with the median salary being $132,478.56. The most expensive goalkeeper salary last year was Troy Perkins of Montreal Impact, who was paid $271,833; $50k more than the average forward salary of $221,506.11. On average though, Goalkeepers have the lowest average rating of all positions in the league, tied with midfielders who have an average Whoscored rating of 6.75. By comparing the salary of a player to his Whoscored rating, you can get some sense of value.

Jeff Attinella of Real Salt Lake was the cheapest goalkeeper in the league last year (tied with Evan Bush) costing just $48,825 but was the 2nd best keeper in the league with a Whoscored rating of 7.11. The best goalkeeper in the league was Bill Hamid of DC United. He had a Whoscored rating of 7.12 and cost $114,750, the 9th cheapest goalkeeper in the league. The 3rd best goalkeeper in the league was also the 4th cheapest - Andy Gruenebaum who cost $85,000.

The two worst goalkeepers in the league last term were Dan Kennedy, now a member of FC Dallas, and Tally Hall of Houston Dynamo, who had Whoscored ratings of 6.33 and 6.37 respectively. Similarly, they were also among the higher paid - coming in at 8th and 7th in salaries. This doesn't look good for FC Dallas, who may be hoping that Kennedy is an improvement on Chris Seitz, or the new Orlando City franchise, who recently signed Hall from Houston for allocation money. Their other new goalkeeping addition, Donovan Ricketts, fared slightly better. He was the 10th best goalkeeper in the league last year with a Whoscored rating of 6.7, but had the 3rd highest salary of $260,000. When Hall is fit to return from knee surgery there looks to be competition for the top GK role at quite an expense.

Taking averages for both salary and performance into account, from last seasons figures you would expect a goalkeeper who produces a performance rating of 6.75 to cost about $132,500. Perkins cost 105% more than the average goalkeeper but produced performances 8% worse, with a Whoscored rating of 6.69. In comparison, Attinella comes at a discount of 63% compared to the average goalkeeper, but his performance of 7.11 is 48% above average. This big decrease in cost and increase in performance shows how much of an undervalued keeper Attinella is. Perkins represents poor budget management; he takes up a sizable chunk of the salary cap and produces poor performances.

Tally Hall, similar to Perkins, cost 61% more than average ($213,500) but his performances come at a 51% reduction on the average goalkeeper (6.37). You’d expect for the money spent, Hall would produce a performance of at least average, not less than half the average ‘keeper. Ricketts had a performance rating of 2.7% above average (6.77) but cost the Portland Timbers 96% more than the average GK ($260,000). As we have seen from the beginning of this article, there is not a strong correlation between salary and performance, but for the investment of 96% over the average GK salary you’d hope for a higher return than 2% above average performance. It’s good to have strength in depth of course - but having two relatively under-performing (and well-paid) goalkeepers is not exactly strength.

Bill Hamid cost DC United 13.8% less than the GK average and produced a Whoscored rating 50% above average. Not as good as Attinella, but still great value for money. Gruenebaum cost 35.8% less than the average goalkeeper and produced a performance rating 25.33% above average. Once again a valuable prospect.

Luis Robles of New York Red Bulls is potentially the most average goalkeeper in the league. His salary was $125,000 which was 5.6% less than the average goalkeeper and he produced a performance rating of 6.73, only 3% less than that of the average goalkeeper - pretty good going and probably the most steady ‘keeper in the league in terms of wage and performance output. This is good for the Red Bulls as it is not really worth them gambling on a goalkeeper who costs more in the hope of gaining a better performance rating. It also means that they can concentrate on getting good players in other positions from the money saved from not over-investing.

From this analysis it’s evident that having the most expensive goalkeeper in the league does not guarantee good performance. It will be interesting to see in the forthcoming 2015 season the performance levels of Ricketts and Hall for Orlando City. Both Gruenebaum and Attinella were available at a lower salary and rated better than them. San Jose drafted Gruenebaum in the Re-Entry draft earlier this month, in my opinion a wise move. We’ll see in 2015 whether his form continues. Attinella on the other hand looks like a good replacement for the aging Rimando, although I’d look to swoop early and take this solid and cheap keeper from Real Salt Lake. As for Hamid I’m excited to see how he progresses through the course of next season for both club and country.

Editor's note: Our own goalkeeper ratings here at ASA are correlated strongly with the WS Ratings with a coefficient of 0.76, and reaffirm the apparent market inefficiency with MLS goalkeepers.