The latest Diablo 3 developer journal has outlined plans Blizzard has for a buff which sets new rules for how mobs will react to crowd control effects. According to the post, crowd control resistance stat which builds when effects are applied and diminishes when they are not will be applied to mobs. There’s a chart any everything explaining how the developers came about the original implementation of CC buff, and how they will change with update 1.0.5 through the link. It should help explain to players why effects diminish as the game progresses. Thanks, >Blue.