MLS Releases Castrol Index - Thierry Henry Best
by Dave Clark on May 12, 2011 8:25 AM PDT
in Sounders: MLS Regular Season
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Major League Soccer has released its version of the Castrol Index (powered by Opta). While this index is being kept separate from the overall index that tracks the big leagues of Europe, it does at least provide a singular ranking based on game data. If one were to do a quarter pole MVP New York Red Bull's Thierry Henry would be on the short list so him being number one is not a surprise. Steve Zakuani and David Ferreira fill out the top three, and so the impact of their loss is even more apparent.
There are some issues with the Index as constructed right now. Some will be corrected over time, and the other is more significant. First is the issue of playing time, because it is so early in the season it looks like not a single Real Salt Lake player met the minimum playing time requirement and so Javier Morales isn't in the top 100. Removing that adjustment and he would be a top 15 player. Which seems more than right. Sadly, we won't be seeing Morales because of the tackle that broke his ankle and earned Marcos Mondaini a 4 total game suspension.
The larger issue is that the lack of transparency means that we must trust that Opta and Castrol have constructed the point values for each action based on how that action effects a team's chance to win. For this we truly only have trust. In the FAQ they say;
A key factor for all areas of performance in the Castrol Index is in which zone on the pitch the action takes place. Players receive points for each successful pass they complete, but the number of points awarded depends on which zones the ball is passed from and received in. Similarly, misplaced or intercepted passes are penalised depending on how much trouble the mistake is likely to land the team in.
Which seems intuitive, and possibly correct. But we can't know, not without the data being tested. Points systems are inherently flawed when based on a few opinions rather than the data.
Context is also missing as all goals are considered equal.
8) Are winning goals worth more than other goals?
No, all goals scored are of equal value.
Which we know is not true. Win expectancy changes based on the timing and number of goals (click through Statistical Analysis to go beyond the initial post on the subject). Factoring that bit of knowledge into their data would be a great adjustment, as it would provide a ranking of the best player similar to baseball's win probability added systems.
But this is what we have now, and the Seattle Sounders injury issues are made clear again as two of the top 15 players in the league are out. The monthly nature of the index means that players with very limited time until May are unaccounted, particularly Tyson Wahl.
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Their claim is that their point valuations are based on goals for/against
but we have no idea which actions are worth what amounts, nor how they are tied to real chances of goals scored.
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They're not, though
If they were, average would be zero and the sum of the absolute value of said points should equal twice the total goals scored in the league.
This isn’t goals, this is a number. It might be useful for fantasy soccer players, but not for anyone taking analytics particularly seriously
by Graham MacAree on May 12, 2011 8:35 AM PDT up reply actions 1 recs
I know in baseball Win Probability is NOT a good way to determine the best players since there doesn't seem to be much of a "clutch" ability.
Is soccer different? Since the system judges each action based on how that action effects a team’s chance to win, goals should be weighted differently like you said. But if we are trying to measure skill, and there is no skill difference between a goal scored in the first min and one scored in the eighty-ninth min, then it really shouldn’t be weighted the same. The same seems true of passes as well. Unless there is something different about soccer, and the skill level that an action (such as scoring a goal) requires differs based difference in the timing and number of goals.
Arguing against my desire for a Win Expectancy Model
Ignores that they have invented their rankings with no direct tie to goals or wins.
But in soccer tactics change later in the game actually should effect the game. Teams with leads tend to play more behind the ball to make scoring late more difficult, while teams without the lead try to adjust and push forward more.
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That's true of baseball as well though
The leverage dictates the quality of pitchers and hitters deployed by each team
by Graham MacAree on May 12, 2011 9:19 AM PDT up reply actions
WAR explanation
This link does a great job of explaining WAR.
As the site explains, “By nature, WAR relies on counting stats (HRs, 2Bs, etc.) to be translated into rate stats (OBP, wOBA) and then combines these factors into value stats. The great thing about WAR is that it takes into account a player’s value both at the plate and in the field, adjusting it for position and park, and compares it to a replacement player.”
For the Sounders the stat you want is: how many more wins can we expect from having Zak on the right flank as opposed to bringing up freely available talent from the MLS reserve league. That number would be Zak’s WAR.
WAR, as well as the rest of the sabermetrics models, are explicitly designed to focus on repeatable individual skills and to ignore the results of those hits. A home run is a home run. Doesn’t matter if it was in the bottom of the 1st or the bottom of the 9th in the World Series.
I think the challenge that sabermertics for soccer is the same for evaluating defense in baseball. The stats heads in baseball have developed UZR, ultimate zone rating, to look at the balls that defenders in baseball should be getting to – not just the ones actually caught.
Something similar in soccer might analyze passes completed, passes correctly handled so that the team retained possession, etc. I like this metric because (a) there are lots of passes in a game and (b) passing is a repeatable skill, and © the number of passes a player attempts is a direct reflection of how involved they are in a game.
(Just one more note. One reason for not weighting the stats in favor of successful goals or passes in high leverage situations is sample size. How many last second goals are actually scored? Also, if you weight in favor of high leverage situations, by how much? Do you want a stat that favors guys who, frankly, got lucky in the last 10 minutes? Or do you want a stat that tells you which guys can keep you from needing last-second heroics?)
UZR
Also known as the “Ferchristsake Jeter Isn’t As Good As You Think He Is” stat. No other player has such an innate ability to make the mundane look spectacular.
Back to your regularly scheduled soccer…
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Playing time does seem to be a big factor
Montano and Estrada have the worst rankings for the Sounders, and (I think) the least time on the field. If it was more WAR-like, they’d be closer to a zero/middle point, since they haven’t had the chance to do much good or bad.
Oh, I wasn't directly arguing against yourdesire for a Win Expectancy Model
In any case a Win Expectancy Model would be interesting and useful. I was just wondering whether the situational context is more relevant in soccer when ranking players (presumably to determine who had the the best performance as a function of skill) then it is in baseball (the sport I am most familiar with).
my goal is to get the right people the data so we can know the answer
and we are working on it.
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Harris is out, too
3 of top 5. And I’d be curious to see where Morales would be if they lowered the minute cutoff. Probably 4 of top 8-10.
Nos Audietis
I'm having a hard time wrapping my head around Harris being in the top 5
He’s a serviceable striker and a better winger. In no way do I consider him one of the top players in MLS.
Also, it says that this is for April stats on the MLS website (right under the title of the article)
It says this is for April stats in which Atiba Harris only made 1 goal and 0 assists (from what I can see on MLS’s website). In April, Montero had 1 goal and 2 assists and is ranked 92nd?
Always remember the Sample Size.
This is a short term measure so far, so there are going to be anomalies. That said, I imagine Harris had a lot of touches in the attacking third (weighted heavily), and I’d guess (based on his top-5 rating) that most of them were successful and that at least some of them were parts of moves that led to goals, or at least opportunities (and so were also rewarded). Castrol might not go far enough past goals and assists, but it certainly does go further past them than most of what’s out there so far.
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Except that they have purely invented the credit they apply to an action
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Of course they have
To get a little more existential than I like to, all systems of measurement are invented at some point.
More seriously, however the system was created, and whatever it is that it measures, Harris excelled at it when he was on the field last month. That’s the crux of my point.
I think your point is probably that they’re measuring the wrong things and doing so in a seemingly arbitrary way, and I think that’s fair. But let’s look at the Index over the course of more than a short month before we dismiss its relevence – we might find that the players it rates highly are the best players on the best teams, or we might find that it’s garbage. Eventually we’ll move past it to another system that is a better gauge of performance vis-a-vis team wins/points, but until Soccer’s KenPom comes along to work out the calculus from the stats (Opta-generated or no), I think “purely invented” measures are what we’ve got to work with.
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by The AMT on May 12, 2011 11:02 AM PDT up reply actions 2 recs
yes
...that's MISTER Keller to you!!!
by malcontentjake on May 12, 2011 11:53 AM PDT up reply actions
My problem with the rankings...
Unless MLS is going to share the stats from which these rankings come, it’s impossible for us to make any sense out of them. They can’t base this on passing stats and ask us to just accept it unless they are also going to share passing stats, IMO.
Editor/writer at Sounder at Heart, MLS editor SB Nation. Follow me on Twitter
by Jeremiah Oshan on May 12, 2011 12:59 PM PDT up reply actions
Spot on.
I’d do a little happy dance in my office chair if MLS and Opta released the raw data. That would allow enterprising fans to play the role of KenPom and the Sabremetricians and that dude in Pi and figure out the pattern. Not to mention the third party tools (chalkboards, whoknowswhat) that would inevitably come our way.
Actually, if it would make it more likely that MLS will release the raw numbers, I promise not to do a little happy dance in my office chair. Nobody really needs to see that.
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by The AMT on May 12, 2011 1:17 PM PDT up reply actions 2 recs
I'm surprised Keller is so low--he doesn't even crack the top 10 and is below 5 of our defenders (plus Ozzie).
It doesn’t appear the system is that low on goalies, since Ricketts is in the top 10. I guess Castrol thinks he should’ve made the saves against the Galaxy and Red Bulls.
Mayer's tweet today about the Sounders and the Index
joshuamayers
I considered blogging about the Castrol Index, which rates MLS players, but the way the Sounders laughed it off today, I think I’ll pass.
I am not a Supporter | I am not a Fan | I am a Sounder
Sounder At Heart
Another thumbs up to this site
For having the right people to analyze this stuff. I’m an analytical guy myself, but I wouldn’t know where to start when it came to analyzing soccer stats. I appreciate that others do, as it’s a fun read (as also evidenced by non-Sounders fans commenting here).
by bmvaughn on May 12, 2011 7:24 PM PDT reply actions 1 recs
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