I'm a little late to this party but.....

I have a MNK main and I do actively switch positions where applicable. In my FC, I regularly party with a DRG that is SO SO good, and together mobs just fall at our feet. On trash, I will mainly utilize a Flank only positioning using DK with him there, he is using his AoE's, and I pop Internal Release at 3 stacks of GL then spam the hell outta Rockbreaker. TP gets low pop Invigorate. Mobs don't even know what hit them.