Not a main MNK, but....
IMO if there is one issue with MNK positional, it is the fact that they just offer potency bonus.
You see DRG's Raiden Thrust? This is a positional bonus done right IMO. The type of thing MNK needs. It doesn't change your gameplay, but it is more visual and significant than a potency change.
Like, instead of True Strike being 30potency stronger from the rear, make it so that if you punch the rear, your next weapon skill is upgraded. And make those upgraded skills 30 potency higher and look badass. For example, make Tifa's dolphin uppercut part of it.
I just think upgrading the ARR combo to something beautiful would be nice, even if it's just visual effects.
Looking at Tifa in FF7R, this is exactly what MNK should be like IMO: fast attacks, moving a lot. XIV obviously tries to replicate that without being an action game. If you take the positional away, MNK becomes a very static job. And all I want is my MNK to be a bit like Tifa (but not as good looking of course).
Other changes that could be good : Chakra should cap at 10 to avoid overcapping.
Some skills still need to be adjusted: All 3 fists, 6-sided, probably anatman too. But truth be told, I don't really care nor do I know what they could/should do with those.
And, if the other melees keep their ranged attack, add Chi Blast, even if you should never use it.
