Deciding to look closer at this I checked the same set of numbers a few minute ago. Previously i would record the numbers at approx 9 AM EST each day. This is 3 PM in Germany. Since as you said the arrivals would be a random arrival queue, it would be a good guess that new arrivals would be as players startup and be a traceable by the hour, with a wave based on demographics and time of day, whereas it would also be my guess that the purge would not be manual, but be some form of script or MySQL DELETE Query run once a day. Now I don't want to track these numbers hourly to graph this out but as i said, i just looked at 4:40 PM, approx 8 hours later, and the number of players is now 54325 and #>0 has increased to 31669, approx 210+ adds. Now we will have to look again at Midnight to see if this is showing a rate off approx 25/hour for new adds. I will go to sleep before midnight and who knows when the script may run. I will look later and report what I find. It is also possible the purge will not run. Still many variables but I think I am now closer to a view of what is happening.
Update 7/10 6:54 EST 54400 Total, 31731>0
.............. 7/10 8:18 -------54446 ------- 31766
Update 7/11 7:20 EST AM 52663 Total, 30089>0
It appears the purge did run last night.
Another quick thought: If the purge is designed to be a continuously run, i would design it to repeat every 30 days so 60,000/30 = 2000 would be my first guess as the best number of purges for the first run through. this would result in a loss of 1400 net if they anticipated 600 new adds per day, after clearing the backlog the number can be adjusted to equal the monthly adds x the 30 day attrition rate. Since the 4 day 100% purge of my own discovered area sample of 115 neighbors only resulted in a loss of about 80% to 90% of my neighbors, a full 2400 daily purge would result in a loss of approx. 2000, so the cycle may end in less than a 30 day first run. say the end of the month.
My current thought is new joins should peek in an hour or two for this US server and the purge should be about 4 AM EST considering a German sys-admin would not want to start the day on a bummer if something failed. so 10 AM German time would allow a cup of coffee and a scan of the system first. We will see.