Bidder 4(who raised the bids about $200) in the Guerciotti auction had 100% activity with the seller.
I don't like the new system either. However, I think that above referenced percentage of activity is more likely that the bidder hasn't bid on anything else in the last 30 days. If they only bid on that one item, 100% of their activity would be with that seller.
I prefer the old system. I like to know who I am bidding against.