Glenn Greenwald points to this Atlantic 50 listing, composed of:
[T]the  most influential commentators in the nation, the columnists and bloggers and broadcast pundits who shape the national debates….Our in-house methodology…:
* Influence: A survey of more than 250 Washington insiders…
* Reach: Comprehensive data collection and analysis to measure the total audience of each commentator
* Web Engagement: …the Wire analyzed top commentators on 16 measures of webiness, including mentions on Twitter and performance on popular social media sites like Digg and Delicious
The final list is the result of an algorithm that brings together these three factors.
Seven of the top ten are Reichwing pundits, two liberal, and the last is Andrew Sullivan.
Paul Krugman is 1st, but Glenn Greenwald is 22nd, Josh Marshall is 29th, and Bill Moyers 32nd. In contrast, Limbaugh, Will, Friedman, Brooks, Krauthammer and Beck are 2-7. Rove, Hannity, Broder and Noonan are 10-13. Rachel Maddow and Arianna Huffington are 14 and 15. And so on in each group of ten making up the top fifty.
Unexplained is the weighting among ephemera such as Twitter hits and "performance" on popular social media sites, and substance or how frequently commentators are proven correct/incorrect. The "top 250" Washington insiders surely listed those to whom they owed allegiance, as self-referential a criteria as one could use.
The list is overwhelmingly rightwing to in extremis. The Atlantic could have saved itself a lot of trouble and algorithms by calling these the Village Fifty. It’s what they came up with. So much for "liberal" as a descriptor of today’s media.