Related Posts : What are they?

Hi Support

I just do not get them. Related Posts I mean.

http://finalbug.net/blog/entry/407-going-mustang-without-a-data-wrangler

How on earth is the above post related to the following?

http://finalbug.net/blog/entry/158-amsterdam-super-meet-11-09-2011
http://finalbug.net/blog/entry/161-about-finalbug-net
http://finalbug.net/blog/entry/201-fcp-x-bristol-event
http://finalbug.net/blog/entry/222-get-the-new-davinci-resolve-9-beta
http://finalbug.net/blog/entry/229-blackmagic-design-cinema-camera-footage-grading-test

The categories are as follows.

My eg Post i.e. Going Mustang Without a Data Wrangler!
Is in the Category Bruce Speaks from Friday, 05 June 2015

The Related posts have the following Categories & Dates:

Events & Tuesday, 06 September 2011
final BUG FAQs & Friday, 31 January 2014
Beginners FCPX & Saturday, 28 April 2012

etc

Is it just me or is there no pattern here!!!

thanks

Paul