As you noted, xandry is the most special case, who was also identified in the analysis of Global structure of merit networks.  You can find him/her in the second last figure.  It might be the case that he/she is focusing on some very active threads and evaluating several users posted there, and those threads are deleted recently.  However, it is not clear why he/she needs to send merit so frequently (see below) and I cannot read deleted posts so it remains unclear to me.