Does Momentum Increase Win % in the LCS?

The announcers love talking about momentum. If a team is coming from a win or two, the announcers comment on their 'momentum' as if it will have an impact on the outcome of their current match.

Will it?

Summary

It doesn't look like it. While individual teams may display streaky behavior, on the whole, teams underperform their previous record the bigger the streak is for both wins and losses.

Method

Using the stats from lolesports for the 2013 LCS (both spring and summer, NA and EU), I looked at a team's current streak coming in to the game, their record coming in to that game, and the outcome of the game.

The 'Actual' bars in the above chart is the LCS record for teams with a streak of that type. The 'Expected' is the average record (win %) for teams with a streak of that type going in to the game. If teams with a 2-game win streak win at a rate of 57.2% up to that point, with momentum we would expect them to do even better. On the flip side, teams with a losing streak of 4+ games only have a 29.4% win rate coming in to that game, yet they win over 50% of their games.

Caveats

To increase sample size I looked at the LCS as a whole. Individual teams may show momentum, but on the whole the LCS doesn't. I also used win percentage rather than raw totals of games played (won and lost) meaning that the record of a team that is 1-0 is weighted as heavily as a team that's 9-0 for the average, this may have an impact on the results.