Flightaware tracking way behind others

Why is Flight Aware’s tracking so far behind (time-wise) than others such as Flightstats? For example, right now Flightstats shows BA 115 approaching the east coast of Ireland on its way to JFK from LHR. Flight Aware shows it as “taxiing”. How is there such a marked discrepancy? Aren’t the two systems using the same data source? I would prefer to use Flight Aware since the information is much richer (track logs, etc.), but damn.