sort_wp_query.php

<?php
$query = new WP_Query( array( 'mrp_sort_highest_rated' => true ) );

/**
 * Adds WP query sort by highest rating then count entries
 * 
 * @param unknown $order_by
 * @param unknown $query
 * @return string
 */
function mrp_posts_orderby( $order_by, $query ) {
	
	if ( $query->get( 'mrp_sort_highest_rated' ) == true ) {
		$order_by = 'adjusted_star_result DESC, count_entries DESC'; // highest rated
	}
	return $order_by;
}
add_filter( 'posts_orderby','mrp_posts_orderby', 10, 2 );

/**
 * WP query join tables for sorting by ratings
 * 
 * @param unknown $join
 * @param unknown $query
 * @return string
 */
function mrp_posts_join( $join,$query ) {
	
	global $wpdb;
	
	if ( $query->get( 'mrp_sort_highest_rated' ) == true ) {
		
		$general_settings = (array) get_option( MRP_Multi_Rating::GENERAL_SETTINGS );
			
		$rating_form_id = $general_settings[MRP_Multi_Rating::DEFAULT_RATING_FORM_OPTION]; // you could remove this from the join if you want
		$filters_hash = MRP_Multi_Rating_API::get_filters_hash( array() ); // if you want to add any Multi Rating pro specific filters e.g. rating_item_ids
		$join .= ' LEFT JOIN ' . $wpdb->prefix . MRP_Multi_Rating::RATING_RESULT_TBL_NAME . ' rr ON ' . $wpdb->posts . '.ID'
				. ' = rr.post_id AND rr.rating_form_id = ' . $rating_form_id . ' AND rr.filters_hash = "' . $filters_hash
				. '" AND rr.rating_item_id IS NULL AND rr.rating_entry_id IS NULL';
	}
	return $join;
}
add_filter('posts_join', 'mrp_posts_join', 10, 2);