WAR, GNB and DRK are generally fairly balanced when it comes to snatching up agro at the start of the fight. This is due to high burst damage - WAR has IR and IC, DRK has Living Shadow and Delirium, GNB has NM + Gnashing fang combo and two dots all with a load of high damaging oGCD attacks.

PLD on the other hand can struggle with snap agro. They do fine in consistent damage, but even though they have FoF they dont really have a hard hitting burst like the other three tanks at the start of the fight. If the PLD is MT and you're OT, consider starting with your stance off and turn it on a bit later on rather than starting the fight with it regardless as to if you're MT or not.