Wiki Stats Missing from Profile
Looks like the bug was introduced in 2.5.7. The wiki stats aren't being added to the Statistics tab because the $key should actually be $hook_key in vault/special_plugins_member.php.
Keep in mind also that vBulletin 4 has no Statistics tab by default, it is included as part of About Me. Also in vBulletin 4 the $template_hook['profile_ministats_list'] is missing, but this is a vBulletin Bug which I have reported.
Fixed for the next build as much as was possible.