An all-too-common mistake that tanks make.

[Sapphidia]

Actually, this is incorrect. You CAN block and parry attacks in FFXIV that come from behind you.

Directional parry/blocking is something that was in WoW and other MMOs. There, yes, mobs behind you would hit you through your evasion/mitigation. In FF though, you can block and parry 360 degrees.

EDIT - This got me curious though, as I'd merely taken this as read from a lot of key guides and discussion forums, so I decided to go and fully test anyway... and you know, I think people are sort of wrong.

You can DODGE from any direction (a dodge just means the mob missed their accuracy check on you, which is level based) but after faffing around with mobs out in the open I've yet to block a single auto attack with my back to things. I've noticed the following -

1 - You CANNOT block or parry "auto attacks" from mobs that come from behind you
2 - You CAN block special attacks with some kind of AOE effect with your back to the mob.

So the OP is actually correct, albeit half-right. You DO take less damage in FF if mobs are infront of you, as that lets you block their weak auto attacks, but you can still block/parry SOME things from behind.