)
Secondly, I have 2 coops ( more if you count the smaller ones .. ) I free range my older chickens because they don't wander very far from the barn. I used to free range my younger chickens but about 2 months ago 3 or more would disapear every day, so they have been locked up ever since. I would get rid of the pest before I would even consider letting them roam.
( Oh, ps. - in case you're wondering what's getting my chickens .. it's a coyote .. )
You have more than enough space for your chickens, so they don't NEED to range freely at all.
However, I'd make sure they get plenty of greens, and if you can capture earwigs or crickets or grasshoppers or other bugs to give them as treats, that would be wonderful. They may or may not have decimated the bug population in the run.....
Bugs have niacin, and fresh greens are good for them too. Of course, they don't NEED anything but their commercial feed, as it's formulated for complete nutrition, but spoiled chickens make happy chickens.