How to Output which matched meta_keys were found from custom_type_posts?

Let me see if I understand your question correctly:

You have the meta values of the player this page belongs to. Then in the loop you have the corresponding meta value of each matched player. All you need to do is compare them:

if($player_position == get_post_meta($post->ID, 'player_position', true)){
    // This player is on the same position as the one this player page belongs to
}

If you have a lot of meta values you should avoid writing a lot of if statements, so better use this:

$meta_values_to_compare = array('player_position','player_height');

$matched_meta= array();
foreach ($meta_values_to_compare as $value) {
    if($$value == get_post_meta($post->ID, $value, true)){
         $matched_meta[]=$value;
    }
}

You can then use this array e.g. to set classes on the element or whatever you need to do.