It's 5AM MST, I'm not surprised.
The point is, while this always had been the least busy time in AH, 2.5 years ago we would have seen around 100 players on the login screen.
Based on my subjective perception: While overall number of players logged in at any given time had dropped over the last 2-3 years, the loss of player at offpeak times has been disproportional high. And this is a trend going on for a long time now.
And I think now comes a snowball effect into play: People may tend to concentrate or shift their play time to a later time, just because there are relatively few players online. Just as a near empty EW or MW makes players chose a different arena. Now they log on, see 50 players and decide to come back later that day. This seems to be supported by the fact that the offpeak arena at euro prime time seems still to run quite well, in regards to palyer numbers.