I've always been intrigued by the catching debate, because in RL I think it makes a significant difference. My best example of how PC makes a difference was last season with these 2 guys:
http://whatifsports.com/HBD/Pages/Popups/PlayerProfile.aspx?pid=2823619 and
http://whatifsports.com/HBD/Pages/Popups/PlayerProfile.aspx?pid=3763499.
Both are good PC's with Mack being at an 83, and Black being a 71. They basically platooned last year, with Black coming in as DR to rest Mack and his sorry DUR rating on days when Mack played. Catching essentially the same guys (with the exception of Black catching my closer with a 2.91 ERA most of the time), Black actually had a better ERA caught with a 3.73 and Mack with a 4.40, even though he has a lower PC rating. Over the past 2 seasons where they have essentially platooned, they have nearly identical defensive stats.