C2 displays the ACTUAL REAL-LIFE fills achieved in brokerage accounts for AutoTraders, when these are available. There are cases where a limit order may not be market-clearing (meaning that some people in the market do get filled at the limit price, but other unlucky people do not). Those unlucky users will be converted to the market price so that they fill the order and stay in sync with the intention of the system.
C2 displays the average real price received, including those who were not lucky and could net get the limit price. This is why, in some cases, the prices you see may be less favorable than the limit prices posted.
You can view how many people got exactly which price, at which trading volume, and at which broker, using our new "Show Real Life Fill" feature. Links to this feature appear near the Recently Closed Trades section of any system that is being AutoTraded.