Modern Warfare 2: The Importance of First Blood

I started doing full game's to determine winning probabilities. In that time, I began wondering "why do games say who gets first blood?" "Why does it matter?" So, I started to, along with all the other stuff I gather, mark which team got first blood and whether or not they win the match. I wasn't too startled by the results but it is intriguing. I found that about 63% of the time, the team that get's first blood goes on to win the game. 

Why would first blood matter that much? How can it have that much predictive power? One hypothesis I thought of was that the more "skilled" player in the match gets first blood and this person contributes a lot to his team and the team ends up winning. 

Modern Warfare 2: Map Breakdown Update

Here is the update. There are now 124 samples and I believe the true probabilities are starting to show themselves. Scrapyard and Skidrow come in first with 10.48%. The expected percentage is 6.25% meaning that if the probability for each map was equal, we should see the maps 6.25% of the time. Scrapyard and Skidrow are nearly double that. Rust is still in last place, I have yet to see it again since I started collecting data.