Season 2 of Glee had an average viewership of more than 10 million people.
Season 3 had an average of about 7 million or so.
The total viewership of 5.79 million fo0r the third episode of this season is an all-time low. It's never dropped below 6 million before. The Season 4 premier episode had ~2 million fewer viewers than the Season 3 premier and .05 million fewer viewers than the Season 3 finale.
We don't have the numbers for last night yet but I'd be curious to see if it rebounded or stayed down.