$array1 =array(2,10,4,5,2,1);
 $array2 =array(A,B,C,D,E,F);



  $ordered_values = $array1;
  array_multisort($array1, $array2);

  foreach ($array1 as $key => $value) {
     foreach ($ordered_values as $ordered_key => $ordered_value) {
       if ($value === $ordered_value) {
        $key = $ordered_key;
        break;
    }
  }


   echo $value . '- Rank: ' . ((int) $key + 1) . '<br/>';

  }

B- Rank: 1
    D- Rank: 2
    C- Rank: 3
    E- Rank: 4
    A- Rank: 4
    F- Rank: 6