You will need to switch from using the week totals over to the day totals and see if you have a specific day that stands out.
Other information that will probably help:
Pull up the views that you screenshot us again, and notice in the left hand corner of your SAP GUI you have a DB Connection Statistics option, anything interesting in there?
Staying with your workload overview screen, next to the times tab you have a database tab, anything interesting in there?
Back to Analysis views > Transaction Profile > Standard find a column that says T Time (Total Time) and sort descending and see what the report or transaction name is that is taking so long, which may lead you to the user who triggered the issue.