Originally Posted by
saevel
Except mobs under your level don't get LCF yet they won't hit you for 0 without phalanx / stoneskin up (negative fSTR zeroing out their base damage notwithstanding)
Go fight a level 38 goblin as a BLU/WAR with defender + cocoon / harden shell up. It's ratio should be way under .5 and thus pDiffmin should be 0. You should see 0's yet you'll see low numbers but not 0's. You see this with brews inside abyssea, go brew Itzpapalotl and let it hit you. You have 9999 defense, its a level 92~95 NM so without a doubt Decent Challenge and absolutely no LCF. It also does not have 1000+ attack, very few NMs have that much. It should be hitting you for straight 0's (50% of time), yet it doesn't.
Monsters have a ratio floor just like we do, except in their case pDiffmin can never hit 0. There is a point at which adding more defense will not do anything, and it's something that easy to hit provided the monster isn't 5+ levels above you.