By Sean Steffen (@seansteffen)
The 2011 LA Galaxy often gets credit for being the greatest Galaxy team of all time, and it’s certainly understandable why. They won the cup. They won the shield, and their ability to put games on defensive lockdown was legendary.
23. That’s how many games the LA Galaxy were involved in in 2011 where the final point outcome was decided by a single goal. This means single goal wins, single goal losses and ties. That’s 68% of the entire season. Of those 23 games, the LA Galaxy won 12, tied 10 and lost only 1, acquiring 46 of the possible 69 points up for grabs. They couldn’t have been more clutch, which is why many (wrong) people consider them greater than the 2014 LA Galaxy team which was statistically superior in virtually every facet. The 2011 LA Galaxy simply took care of business.
That’s the narrative, at least. However, it belies a simple truth of soccer which is hard to fathom for the casual fan but is undeniably apparent when looking at data from around the world. Luck plays a huge factor in goal scoring.
Now, I’m not saying that goal scoring is just a random roll of a dice and that skills like finishing don’t matter. They most certainly do. I’m saying that chance and probability have a much larger role than most people think.
Think of it like darts. To get a bulls-eye, a number of estimations have to be made perfectly and the execution has to be perfect. While a player will never be perfect in hitting the bulls-eye every time, the better they are the more closely their darts will group around a target over multiple throws. In this way, skill is tied to consistently getting darts in the area, and probability determines where in that area it’ll fall. In other words, the more skill you have, the smaller your range and the more likely you’ll land a bulls-eye.
Striking a soccer ball is almost exactly the same. When a player takes a free-kick, there are a lot of factors in play. The player has to correctly determine the distance of the shot and how much movement the ball will require to hit the target in order to gauge how much force and spin it will take to put the ball on net.
One could fairly precisely determine where the player must strike it and with how much force in order, using physics, however, getting out the protractors and calculators would probably slow the game down a bit too much for most fans, so that’s not how it works. Instead, players work off mental estimations and muscle memory, both of which can be improved with practice.
This marriage of skill and probability is why some soccer players are undoubtedly better at placing balls than others, but no player can place a ball exactly where he wants every time. This is true for every shot a player takes in a game, which is why chance has such an impact on goal scoring. For this reason, goal scoring in a single game can be extremely chance dependent.
So what does this have to do with the LA Galaxy in 2011? Loads, when you think about it. If goal scoring is not something that is completely controlled by skill, it makes you wonder how much chance played a role in those 23 games the Galaxy played that year where a single goal would have swung points. Sure that team was great defensively, but a better taken shot here or a different bounce there could have easily lost the Galaxy the supporters shield. At the same time, a different bounce here or a better shot there could have turned a few of those ties into victories, punctuating their dominance further.
So the question remains. How much did luck play a factor on the LA Galaxy points total in 2011, and in which direction? The best way to test this is to strip the outcomes of shots and simply add up the probabilities as measured by expected goals.
So let’s dive into the data, shall we?
I used an expected points model of my own creation to determine the likelihood of the Galaxy reaching the points total they did in these goal swing games. The parameters are simple. Games with an expected goal differential (xGD) between -0.3 and 0.3 are assigned a tie. Games above the range are tallied as wins and games below are tallied as losses. Here is that data:
As you can see, the Galaxy fall well below the points total they ended with over these games. This would suggest that they were indeed lucky. If you narrow the tie range to -0.20 to 0.20, the expected points jump up to 39. It’s better, but the Galaxy still come out looking lucky.
If you examine the Galaxy’s total goal differential over these games, 0.012599, you’ll see that it doesn’t lean very far in either direction, which certainly lends credence to the fact that the Galaxy were not nearly as dominant over these games as you’d expect of a team coming out with 67% of the points in one goal scenarios.
This lines up nicely with the xGD stats for the Galaxy as whole that season. Over the entire season, their average xGD per game was -0.10. They succeeded by out producing that to the tune of 0.66. Of course, not all of this can be attributed to luck.
It’s a well known fact that counter attacking teams tend to outperform their xG. Counter attacking teams take more shots against fewer defenders (something the model doesn’t take into account) and get more players in front of shots. Another factor is the model breaking set-piece accuracy of David Beckham. 32.3% of LA’s goals came from set-pieces. 13 of the 46 points LA accrued goal swing games, are the result of a set piece.
So what are our final conclusions? When you look at all the data, it certainly seems like lady luck was on the side of the LA Galaxy, but not by a wide margin. Given the LA Galaxy only beat out the Seattle Sounders to the Supporters Shield by a mere four points, it is not unreasonable to suggest that it may have been a determining factor in the outcome of that trophy. Ironically, lady luck aided the Seattle Sounders in 2014 when they beat out a statistically superior LA Galaxy for the very same trophy, so perhaps all is fair in love and supporters shields.