My understanding is that it would sort just the field, not the entire row.

Not quite. Look at this small example:

use strict;
use warnings;
use Data::Dumper;

my @items = (
    [0, 4, 2],
    [2, 5, 8],
    [-5, 0, -3],
    [3, 4, 0],
    [1, 4, 8],
);

my @sorted = sort { $a->[1] <=> $b->[1]  } @items;
print Dumper \@sorted;
__END__
$VAR1 = [
          [ -5, 0, -3 ],
          [ 0, 4, 2 ],
          [ 3, 4, 0 ],
          [ 1, 4, 8 ],
          [ 2, 5, 8 ]
        ];
[download]

(I tidied up the output a bit to include less line breaks).

You can see that the array is sorted by the second column, but the result is a list of array references, just like the input.

sort is very powerful, you only have to know how to use it ;-)