It is pretty hard to win if you are not in the top 2. The past 4 years of combined results are in the attached chart. More than 80% of the time, the winners are one of the top 2 alliances.
As Al said above, this is because the best teams seed highest. This means that the seeding system works properly.
Thats why you one of the best Jim, I always love your charts... Perfect way, to show the spread the winners of events...
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Team Member- 326 2006-2009
Team Mentor- 326 2010-2013
Team Mentor- 313/5220 2014-??