Thanks Jorge for the mini-analysis.  I'm the developer of that site.

The plot you linked is a dynamic one; so here is the static plot of that time interval:

http://i.imgur.com/dVzx0BL.png

And the same graph, but scaled for viewing of the tx byterate:

http://i.imgur.com/MEfBHg7.png

Some things to note (I should have added this on the site, ideally):

1. The tx byterate estimation is done using a exponential moving average, with a halflife of 1 hour.

2. The capacity byterate is given by

blockrate * expected max block size

where expectation is taken over the mining pools; estimates for pool max block size policies can be found here.