I think , you should test the formula first in some random samples.

Name:   soniclord
Posts:   1997
Activity:   1092
Merit:   1002
Position:   Legendary
Date Registered:   April 05, 2015, 07:12:51 AM
Last Active:   July 16, 2018, 03:21:23 AM


WoP = (Merit + 1) / Posts x Activity
        =(1002+1)/1997*1092  =548.46

By your formula,soniclord is more worthy poster than all of the below quoted.

Its a rough guide for determining the potential chance that what somebody has to say is going to be interesting. Of course its not an absolute measurement of anything in particular,