# THIS doesnt mean \\server_name\sys_share it means \server_name\sys_share
$unc = '\\server_name\sys_share'; 

# and then you remove the leading "\" and trailing "\sys_share" before the benchmark even starts!
$unc =~ s/^\W*\w+//;
$server = $&;
$server =~ s/^\W+//;
# None of the regexes in the benchmark will match anymore (in a meaningful way)