It looks to me like the altitudes displayed in the log reflect not only the actual altitude but occasionally the assigned altitude. For example, while cruising at 290 the altitude of the next data block shows 210. Then it jumps back up to 288 and slowly progresses to 210. Does the controller input the fact that he has cleared the flight to 210 and this shows up as the actual altitude in FlightTracker’s data for one cycle?
Wow! You have a lot of time on your hands!