"Block speed" is the aviation term for "door-to-door". While the average speed for your flight pertains to mean airspeed, block speed is the average speed given over the distance from the departure gate to the destination parking spot.
For a safe and on-time departure, there are many important things that need to happen between boarding and actual take-off. If the aircraft is boarded from the terminal, a crew must attach a push-back vehicle to the aircraft with a tow bar, push the aircraft away from the terminal to an open area where the pilot is safe to start the aircraft engines, disconnect the tow bar from the aircraft, and signal to the pilot that all ground crew and equipment are clear of the taxi-way. The pilots must wait for permission from the control tower to taxi, and then the slow roll to the active runway begins.
In these ground duties and flight preparations, teamwork is measured as part of the block speed. Monitoring to optimize block speed ensures the provision of a punctual and safe operation.