The Ensemble is actually a meta-team of most of the teams that didn't participate in BPC, and I'm hearing that BPC had lately tried to get some other teams to join, so they were kinda expecting that (but I don't think they will be able to fire back).
Bottom line, I think that the most massive open data set out there (next to a competition) has really helped the research to move on, but I don't see the point in 5 or 10 teams joining forces to improve the results for a tiny percentage and win the prize.
On the other hand, maybe this is actually the right thing, for all these teams that have struggled for two years to be in the top-15 to receive the prize...