Strange indeed. I get similar results, although with smaller differences. However, if I change the tests (but not the regexes or the data) slightly, I do get the results where unpack wins: 
#! perl -slw
use strict;
use Benchmark qw [cmpthese];

our @data = map{
    join' ', '2004-05-13', '14:02:00', ('blah') x (1 + rand (9))
} 1 .. 1000;

our (@greedy, @explicit, @unpack);

cmpthese (-1, {
    greedy   => '@greedy   = map {/(^\S*)\s(\S*)\s(.*$)/}        @data
+',
    explicit => '@explicit = map {/(^\d{4}\-\d{2}\-\d{2})\s
                                   (\d{2}:\d{2}:\d{2})\s(.*$)/x} @data
+',
    unpack   => '@unpack   = map {unpack "A10 x A8 x A*" => $_}  @data
+',
});

die unless "@greedy" eq "@explicit" &&
           "@greedy" eq "@unpack";

__END__

           Rate explicit   greedy   unpack
explicit 86.1/s       --      -6%     -25%
greedy   91.6/s       6%       --     -20%
unpack    114/s      33%      25%       --

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Abigail

In reply to Re: fast greedy regex by Abigail-II
in thread fast greedy regex by js1

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