Yep...ditto the grass thing.
My run is a 20x80 foot section of our backyard that I partitioned off for the chickens.
It took my 8 girls about 4 weeks to take that area down to mostly bare earth....
I'd say drainage IS the more urgent issue - if it's a well drained area they'll be fine. If a low spot where water tends to collect you'll have a muddy, stinky mess in a very short time.
My run is a 20x80 foot section of our backyard that I partitioned off for the chickens.
It took my 8 girls about 4 weeks to take that area down to mostly bare earth....

I'd say drainage IS the more urgent issue - if it's a well drained area they'll be fine. If a low spot where water tends to collect you'll have a muddy, stinky mess in a very short time.