Ninja doesn't really need a nerf. In boss fights it still doesnt match a monk. A ninja will be top in fates and dungeons. Fates because positionals dont matter. If a monk has aggro he will lose aggro to a ninja due to the terrible potency from missing every positional with the occasional 1 or 2 from stunning. Dungeons due to next to no ramp up time. A monk isnt using PB on random trash mobs so it will slow the dungeon as he loses gl3 and builds it back up between every mob pull.
Monks get an extra 22% damage over ninjas and they may had closed the gap but monk is still top single target dps