Your problem reminds of this old node: Rosetta code: Split an array into chunks

Adapting that code to your problem shows how we can employ functions from List::MoreUtils to this problem.

use strict;
use warnings;
use List::MoreUtils qw(part natatime);
use Data::Dumper;

# Load test DATA below into an array of teams (adapted from original n
+ode)
my $line;
my @teams;
while ( $line = <DATA> ) {
      chomp $line;
      if ($line =~ /^#/ || $line =~ /^\s*$/) {
           next;
      }
      $line =~ s/^[^=]*\=//;
      push @teams, split( /,/, $line );
}
print Dumper \@teams;

# ------------------------------------------------------
# Adapted from https://perlmonks.org/?node_id=861938

# Using natatime
sub chunk_array {
    my ($n, @vals) = @_;
    my $str;
    my $iter = natatime($n, @vals);
    while ( my @line = $iter->() ) {
        $str .= join(",", @line) . ",\n";
    }
    $str =~ s/,$//;
    return $str;
}

# Using part
sub chunk_array_2 {
    my ($n, @vals) = @_;
    my $str;
    my $i = 0;
    $str = join "", map { join(",", @$_).",\n" } part { $i++/$n } @val
+s;
    $str =~ s/,$//;
    return $str;
}

my $v1 = chunk_array(3, @teams);
print "Version 1--------------\n";
print $v1;

my $v2 = chunk_array_2(3, @teams);
print "Version 2--------------\n";
print $v2;

#---------------------------------------

__DATA__
Teams=PATRIOTS,BILLS,DOLPHINS,JETS,COWBOYS,GIANTS,EAGLES,REDSKINS,BENG
+ALS,OILERS,STEELERS,BROWNS,SEAHAWKS,RAMS,49ERS,RAIDERS
[download]

Running the test program above produces:

$VAR1 = [
          'PATRIOTS',
          'BILLS',
          'DOLPHINS',
          'JETS',
          'COWBOYS',
          'GIANTS',
          'EAGLES',
          'REDSKINS',
          'BENGALS',
          'OILERS',
          'STEELERS',
          'BROWNS',
          'SEAHAWKS',
          'RAMS',
          '49ERS',
          'RAIDERS'
        ];
Version 1--------------
PATRIOTS,BILLS,DOLPHINS,
JETS,COWBOYS,GIANTS,
EAGLES,REDSKINS,BENGALS,
OILERS,STEELERS,BROWNS,
SEAHAWKS,RAMS,49ERS,
RAIDERS
Version 2--------------
PATRIOTS,BILLS,DOLPHINS,
JETS,COWBOYS,GIANTS,
EAGLES,REDSKINS,BENGALS,
OILERS,STEELERS,BROWNS,
SEAHAWKS,RAMS,49ERS,
RAIDERS
[download]

References Added Later

• Scalar-List-Utils by Paul Evans
• List::Util (core Perl module)
• Scalar::Util (core Perl module)
• Sub::Util (core Perl module)
• List::UtilsBy by Paul Evans

• List::MoreUtils by Jens Rehsack (included with Strawberry Perl)
• List::SomeUtils by Dave Rolsky
• List::AllUtils by Dave Rolsky