my ( $top_entry, @entries ) = @_;
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You understood correctly. My mistake was in not realizing that the subroutine arguments (correct me if I'm wrong) would automatically be $_[0] ($top_entry) and @keepers (@entries).

Thanks for your help so far. I feel like I may be a few steps away from accomplishing my scripting goal.

Great to hear! And yes, that's the way the code is working.

Since you may not be familiar with this type of assignment, I just wanted to clarify something about this line:

my ( $top_entry, @entries ) = @_;
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The order of scalar vs array is really important. For example:

#!/usr/bin/env perl
use strict;
use warnings;
use feature 'say';

my @original = qw(a b c d);

my ( $first_item, @the_rest ) = @original;
say "First item: $first_item";
say "The rest: @the_rest";

my ( @array_first_bad, $last_item ) = @original;
say "Array first is bad: @array_first_bad";
say "Last item: $last_item";

__END__
First item: a
The rest: b c d
Array first is bad: a b c d
Last item: 
Use of uninitialized value $last_item in concatenation (.) or string a
+t line 16.
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