If we get Zaun, we have to expose George Kottaras to waivers. As hard as it is to find a decent catcher I doubt Kottaras clears waivers -- too many teams have an absolute gap at catcher for me to believe teams will pass up on a chance to get him for free, especially with the power he hit for a couple years ago in AAA.
Kottaras isn't a great backup catcher, but he's serviceable and young enough to improve. I don't think the difference beween him and Zaun is all that great and he's probably a better bet than Tek going forward.
Even leaving Kottaras aside, I'd like to give Dusty Brown a shot before spending money on Zaun. There's other places the Sox need to put their dollars this offseason than a going-on-39 year old backup catcher with no arm. We already have one of those, only younger. And believe me, if that .800 OPS of Zaun's last year isn't small sample size, nothing is.