yea, I've knocked around the SW also - but I try not to confuse observing with knowing (not really even my opinion, see below)
"
While the Mesoamerican ball courts were generally built out of stone, in the Arizona desert the Hohokam built theirs by digging into the desert and piling the soil up on either side. Some of the ball courts were 250 feet (76 meters) in length and 90 feet (27 meters) in width. In some instances they were dug up to 9 feet (nearly 3 meters) into the subsoil."
from
Hohokam Ball Courts | Native American Netroots
Obviously I saw, and commented on, the photos showing stacked rocks on the sides; more on the 'net through I could find no rocks in others.
not a biggie, much more photogenic this way