Playing games with split :)

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11124600
use warnings;

my $line;
my @teams;

while ( $line = <DATA> )
  {
  chomp $line;
  if ($line =~ /^#/ || $line =~ /^\s*$/) 
    {
    next;
    }
  $line =~ s/^[^=]*\=//;

  my $count = 3;
  while( length $line )
    {
    push @teams, [ split /,/, $line, $count + 1 ];
    $line = defined $teams[-1][$count] ? pop @{ $teams[-1] } : '';
    }
  }
use Data::Dump 'dd'; dd \@teams;

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