I am not a developer, so I will try to help You as a I can.
Well, You can try 2 things.
This plugin shows stats about the best witch killer and
this one shows stats about pounces (I use this in my L4D2 versus server and works fine).
So... You can read the codes and try to get what you want.
The another thing is send a PM to DieTeetasse (first plugin) and ask Him to help You.
Good luck!