In May 2009, @Mashable, @TechCrunch and @BoingBoing were about equal as three of the biggest blogs on the planet. Each had about 1.85-1.90 million unique visitors in that month.

Fast-forward just a year later, and everything has changed. BoingBoing has dropped almost a million visitors, TechCrunch has gone nowhere, and Mashable has gained a million.

Why? Twitter.

@Mashable has over two million followers. Twitter started to really take off early in 2009, and Mashable totally capitalised. Twitter has easily become their primary focus point – they write a ton of Twitter content, and share heavily on the network. (As a comparison, Mashable has ‘just’ 207 thousand fans on Facebook – a tenth of the network size.)

@TechCrunch has a little under 1.4 million followers, but they don’t push anywhere near as hard as Mashable does on Twitter. That said, it’s enough to keep them in the game. (54,210 Facebook fans.)

@BoingBoing has just 43,219 followers. And doesn’t push hard at all. Indeed, BoingBoing isn’t even on Facebook. Which suggests to me that they either don’t really get the value of social media, or don’t think that they need it. For example – they don’t even use a retweet button on their blog.

After all, let’s face it – BoingBoing and Mashable aren’t all that different. Both are heavy recyclers of external content (although Mashable does write a lot more original material – TechCrunch is almost all original material and opinion). The main difference is Mashable is very much more attuned to the modern social media audience, both in content and presentation. Indeed, they made dramatic, intentional adjustments to capitalise on that audience shift.

BoingBoing did nothing. And until they realise that, and want to change, their numbers are probably only going to get worse. They’re still thinking old-school – Digg, Reddit, Delicious and Stumbleupon. And while you can still get some traffic spikes from those sources, it’s very much on the wane, and doesn’t begin to compare to the Terminator-like, never-ending, cannot-be-stopped onslaught of Twitter.

(Disclaimer: Yes, I know this is Compete, and yes, I know that this mostly represents US traffic. But unless you can prove to me that the relationship between these numbers is dramatically different around the world – and can show me where you get those numbers – it’s largely a moot point.)