WP_Query ordinamento per valore numerico dei termini della tassonomia

Ecco la query complessa che ho utilizzato per ordinare numericamente e filtrare la query dei post in base agli slug delle tassonomie.

$my_post_type = 'some_post_type';
$my_term_slug_to_be_used_for_Ordering = 'some_slug';
$my_term_slug_to_be_used_for_Filtering = 'some_other_slug';

$querystr = "
  SELECT 
   $wpdb->posts.*, $wpdb->term_relationships.object_id, 
   (SELECT wpt.slug
        FROM $wpdb->term_taxonomy wptt 
        INNER JOIN $wpdb->term_relationships wptr ON wptt.term_taxonomy_id = wptr.term_taxonomy_id
        INNER JOIN $wpdb->terms wpt ON wpt.term_id = wptt.term_id
        WHERE 
        wptr.object_id = $wpdb->term_relationships.object_id AND 
        wptt.taxonomy = 'my_term_slug_to_be_used_for_Ordering') AS numeric_column_value

    FROM $wpdb->term_taxonomy INNER JOIN $wpdb->term_relationships ON $wpdb->term_taxonomy.term_taxonomy_id = $wpdb->term_relationships.term_taxonomy_id
         INNER JOIN $wpdb->posts ON $wpdb->posts.ID = $wpdb->term_relationships.object_id
         INNER JOIN $wpdb->terms ON $wpdb->terms.term_id = $wpdb->term_taxonomy.term_id
    WHERE 
         $wpdb->terms.slug = '{$my_term_slug_to_be_used_for_Filtering}' AND
         $wpdb->posts.post_type = '$my_post_type' AND $wpdb->posts.post_status = 'publish'

    ORDER BY numeric_column_value * 1 DESC"; // È effettivamente una stringa, quindi * 1 per il valore numerico

$r = $wpdb->get_results($querystr, OBJECT);

Certamente, nel parametro orderby, esiste un'opzione chiamata meta_value_num che dovrebbe fare esattamente quello che stai cercando.

http://codex.wordpress.org/Class_Reference/WP_Query#Order_.26_Orderby_Parameters

$press = new WP_Query(array(
    'posts_per_page' => -1,
    'post_type'      => 'individual',
    'post_status'    => 'private',
    'orderby'        => 'meta_value_num',
    'meta_key'       => 'individual-group'
));