you are writing "If your python < 2.6, it requires simplejson" - but the source you are offering requires simplejson anyway, undepending any version of pyton.
you are writing about compatibility to trac0.12 on the projects site "2011-01-10: Trac 0.11 and 0.12 (trunk) compatible versions are now available. The Trac 0.10 version is no longer supported. " - this is not given; the plugin runs unstable and causes Internal Server Error from time to time or even "No handler matched request to /stractistics"
i took http://trac-hacks.org/changeset/latest/stractisticsplugin?old_path=/&filename=stractisticsplugin&format=zip as you wrote on the project's page, and compiled the trunk to an .egg
to get this run in trac0.12.2 i made some changes to the trunc/stractistics/web_ui.py :
### this is line 33
# from http://stackoverflow.com/questions/712791/json-and-simplejson-module-differences-in-python
try: import simplejson as json
except ImportError: import json
# changed any "simplejson" in this file to "json"
i installed as a plugin into the trac-folder running python 2.6