They changed everything a month or two ago. Here's the article from Help & Support:
https://support.chess.com/customer/portal/articles/1622811-how-are-seeks-matched-in-live-chess-
And here's the main thread:
http://www.chess.com/forum/view/livechess/new-logic-for-auto-pairing-and-seek-graph
Hi,
In the past, I was able to specify a rating range before hitting "start game" button. Now this is not possible. (I can only specify rating range for the graph).
And what i see on the graph is not a lot of people. Is there a decrease in number of chess.com users online?