I don't think you can treat chickens as you would herbivores on pasture, as chickens don't actually graze. They will pick and choose sprouts and some greens, but they won't graze the area down.....more likely they will trample, dig and scratch, and bald some areas while other areas will grow up and the weeds will gain dominance. Changing their grass rotation will help keep areas from being decimated and will give them better choices, but I think the good annuals would not replenish theirselves and the good perennials would not flourish unless you are actually managing the grass.
Now, if you were to rotate your chickens after an herbivore or two, like some sheep, you would definitely develop your beneficial grasses, the more nutritious perennials and annuals, the chickens could keep your parasite load down by eating the larvae and scattering the droppings(therefore increasing the benefit of the manure), and you could benefit from two species being on the same graze.
Depends alot on if you just want to avoid bald ground or if you are interested in developing nutritional food sources for the chooks. If its the former, simple rotations will keep from balding but will have to be mown down. The latter will have to have some other form of graze managing to produce better pasture.