If it's any consolation, the last time I fired up Blur on 360 and also had Live, from memory there were literally hundreds of people still playing it. This was during daytime on the weekend as well mind you, so (from what I understand) prime-time gaming time overseas.The decline seemed to happen around the time Blur and Split/Second bombed. I guess publishers/developers everywhere saw those bomb and decided the market wasn't there any more.
Still haunts me that Blur wasn't as well received as it should have been. Acti really screwed the pooch on that one with their absolutely idiotic marketing campaign.