"I've saved about 15 flags from being repicked with it"
That doesn't imply that those games were otherwise lost. Maybe you stunned someone that was going to repick the flag in horde base when he was surrounded by all horde team without any support. Maybe if you were better positioned you could have just feared them. Ofc, I've killed some efc, even some repickers, have i saved the bg? Maybe, maybe not, that why it's called "teamwork". Yes, chastise effects seem more visual, you can say "hey, i prevented that guy from repicking, holy spec ftw". Disc is not so visual, but i usually do about 20k damage per bg. Maybe i casually killed the guy who later was going to repick and that why he wasn't there and didn't repick. See? Same effect, but less visual.
Anyway, maybe you enjoy wsg a lot but for me is meh. I took my decision of playing discipline because of arenas. I like to play mage/priest and combining both bursts we kill anyone quite easily, arcane missils + penance while enemy is trying to los us is funny ;P