Other than the fact Werth played all year and Difo barely played at all...you make an excellent point. You contend Werth is a "giant freakin' black hole" and there is absolutely zero data to back that. He's basically average. That's what the data says. That's not a black hole. You are being dramatic.
Play Difo in LF all season and he'll have a higher WAR than Werth.