My first coop had chicken wire all the way down to the ground. The possums would get one on each side at night, bounce the chickens from side to side (chickens are stupid at night) and then they would grab one through the wire and extrude them through the wire eating as they went. Within a month they were all gone. The whole thing was very disturbing.
My new coop has plywood sides with hardware cloth (1/2" squares) on the upper part. As in the article, mine is closed in with plywood siding on three sides (1/2 way on the ends) and open at the top on the remaining sides with siding on the bottom part (all the way around) The closed in area has the nesting boxes. I did a closed in room behind the nesting boxes so I can access the boxes by lifting a small door in each box on the rear wall.
In the chicken run area, I used chicken wire at the top and roof but I used hardware cloth for the first two feet off the ground.