LCS and Momentum Revised

After getting some helpful comments on reddit, it turns out my methodology may have been lacking. This is what CaptCarmine said:

I actually think you have skewed results becuase of the differing level of skills of teams in Both leauges, if you have a 2-3 win streak it can be because you have dodged a stronger team for a couple of games

Excellent point indeed. I assumed a win percentage equal to the current record of the team with the streak, I did not take in to account the opponent's record. So I went back to the data and tried to make CaptCarmine happy.

Summary

While the data has slightly more noise, the results are still quite similar -- momentum does not seem to make the teams more likely (in aggregate) to win games than if they don't have a streak. What is clear is that teams with longer streaks generally have better records (and a higher expected chance of winning).

Actual vs. Expected Winning Percentages by Streak

With one win, teams marginally outperformed their expectation, but the longer the winning streak, the less likely it seems to be that it contributes to a win. Loss streaks are much less clear. Momentum in the negative direction may carry more weight.

Method

I summed up the games and wins of each team and their opponent on a streak. I summed up the totals so that we have a bigger data set to work with.

Caveats

Teams who both have streaks are currently included, which means that if two teams have winning (or losing) streaks, one is bound to break theirs no matter what.