#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dump;

my @positions = qw/QB RB WR WR WR TE FLEX DST/;

my $str = 'QB Carson Palmer RB Chris Ivory RB Eddie Lacy WR A.J. Green WR John
Brown WR Davante Adams TE Martellus Bennett FLEX Jeremy Hill DST Panthers';

my $ds;
my $currentPosition;

for my $word (split /\s+/,$str) {
    if (my ($position) = grep { $word eq $_ } @positions) {
        $currentPosition = $position;
        push @{$ds->{$currentPosition}}, [];
    } else {
        push @{$ds->{$currentPosition}[-1]}, $word;
    }
}

dd $ds;

{
  DST  => [["Panthers"]],
  FLEX => [["Jeremy", "Hill"]],
  QB   => [["Carson", "Palmer"]],
  RB   => [["Chris", "Ivory"], ["Eddie", "Lacy"]],
  TE   => [["Martellus", "Bennett"]],
  WR   => [["A.J.", "Green"], ["John", "Brown"], ["Davante", "Adams"]],
}