Central Winger: Is the Portland Timbers' 11-game unbeaten streak "lucky"?
Thirteen games into the 2013 season, the Portland Timbers have only lost one match and currently find themselves running fourth in the Supporters' Shield race. What's perhaps even more impressive is that they're currently on an 11-game unbeaten run.
In a league like MLS, where any team can beat another on any given day, this is particularly impressive. But just how exceptional is it?
In the 323 regular-season games of the 2012 MLS season, 167 were won by the home team, 79 were won by the visiting team, and 77 of them resulted in a draw. With home teams winning more than half their games, and drawing another quarter, they averaged 1.79 league points per match. Conversely, away teams averaged 0.97 league points per game.
Using last year's statistics as a baseline, we can use something called a Monte Carlo method to simulate thousands of MLS seasons in a matter of seconds. This allows us to determine just how exceptional Portland's unlikely 11 game streak actually is.
And it's impressive. An average MLS team has a 1.49 percent change to go on an 11-game unbeaten in a single season. That's once every 67 seasons. Again, this is only for the average MLS team – where half the teams they play are stronger than them and the other half are weaker (and assuming the talent distribution is close to normal).
For stronger-than-average teams, going on an 11-game unbeaten run is considerably easier. But just how above-average are the Timbers? It's impossible to tell exactly. This is because there isn't a tried and true method for identifying the influence of luck on a particular game (or season).
However, I think we can at least glean some insight.
In this simulation, as expected, we saw a positive correlation between a team's league points and the length of their longest unbeaten run. The teams that had longer streaks generally scored more league points – no surprise here. In fact, a the length of a team's longest unbeaten run could account for 20 percent of the total variance in a team's final point total.
An average MLS team is expected to have at least one sequence of five unbeaten results. When we compare the expected league points for these average teams against exceptional teams like Portland (unbeaten in 11), we see two diverging distributions.
The difference between these two distributions is representative of skill difference between the average MLS squad and this season's Portland Timbers. Since the two series haven't completely diverged, it's entirely possible that Portland is just an exceptionally lucky "average" team.
But it's unlikely.