An ineffective bullpen cost the Kansas City Royals dearly in a 6-5 loss to the Seattle Mariners on Wednesday night at Kauffman Stadium. Royals reliever James McArthur operated as an opener and surrendered three runs in his lone inning. Mariners outfielder Julio Rodriguez hit a leadoff double and catcher Cal Raleigh hit a two-run homer. The Royals allowed six walks in the game. Rookie pitcher…