I don't think that is right, it says that automattic has 2000 servers but they also run things like gravitar, akismet, and vaultpress. Which makes me think that using that number is completely wrong. (Also these are just the load balancers not the back end, which could be taking up a large amount of that 2000 server count)
From the article it seems more like they have ~100, maybe less, for the load balancers which comes out to 175 requests/second per cpu which is getting a little more reasonable.
Of the 2000 servers, about 90% of them are running something related to WordPress.com. There are 36 "load balancer" servers in total. I added up the req/sec across those 36 machines and came up with the 70k/sec number in the article. The requests aren't evenly distributed across that subset of machines though, so you can't just divide evenly to figure out a req/sec/CPU rate. I left another comment in this thread that mentions 5k req/sec on a "normal" load balancer and that the limiting factor isn't Nginx CPU usage.
If this is just about load balancing, then they could probably get better performance from haproxy, right? Anyone should be able to exceed 200 req/s with haproxy. In fact, you should be able to get around double that or more.
The point is the title is useless. It tells you almost nothing. That blog is a joke.
Well it is average req/s so peak should be much higher, and they probably can average much more than what they are doing now in case of spikes and other such things.
From the article it seems more like they have ~100, maybe less, for the load balancers which comes out to 175 requests/second per cpu which is getting a little more reasonable.