Investigate peak in MySQL throughput
Anaylzing binlogs may not give you an accurate picture because binlogs contains queries that were completed and are inserted in the binary logs like a FIFO queue.

What you really need to look for is what does the historgram of actively running queries looks like. In other words, you need to catch the processlist in the act of revealing what queries and what performance was like when the unique circumstances came into existence.

I highly recommend using the pt-query-digest but you need to use itt differently. Instaed of have the query digest process the binlog entries, have it process the processlist LIVE !!!

I wrote a past post (Nov 24, 2011) on how to use the pt-query-digest (My post uses mk-query-digest) as a replacement for the slow query log (I have posted the actual script I used plus how to read the query digest output) : MySQL general query log performance effects. My past post was based on a YouTube Video showing how to do it. I just simply emulated myself using mk-query-digest.