When I look at my ranking for a game I can't find anywhere to see TOTAL number of players. If I'm ranked 120th, it's a big difference if there are only 125 players or 30,000 players. How can I find out?
Except those who have voluntarily left the group. That's also truly "all-time", while the ranking is only for those who have played at least once in the past 2 months (or for the current Arena season, if that's what you're looking at).
For example, The current "all-time" ranking (i.e. fake "all-time") of Lineae has 21 players, but the Lineae players group has 1122 members (including BGA admins and developer).