Fix bugs, use plural post slugs, move actions and filters into hooks folder

admin/hooks/wp-insert-post-data.php

@@ -0,0 +1,19 @@
+<?php
+function sportspress_insert_post_data( $data, $postarr ) {
+  
+	if( $data['post_type'] == 'sp_event' && $data['post_title'] == '' ):
+
+			$teams = (array)$postarr['sp_team'];
+
+			$team_names = array();
+			foreach( $teams as $team ):
+				$team_names[] = get_the_title( $team );
+			endforeach;
+
+			$data['post_title'] = implode( ' ' . __( 'vs', 'sportspress' ) . ' ', $team_names );
+
+	endif;
+
+	return $data;
+}
+add_filter( 'wp_insert_post_data' , 'sportspress_insert_post_data' , '99', 2 );