You may think grass grows in soil. It doesn’t. The roots actually grow in air spaces between soil particles.
Imagine the soil is like a sponge, there are some pockets we want with air and some we want with water.
A soil with lots of air pockets will allow water to freely drain through the soil profile. This is why we “spike” the turf to create these air pockets.
If we start walking on these soils when they are saturated then a lot of those little pockets get closed up and water can’t move through as easily and it takes a lot longer to dry out.
When the ground is at saturation point gravity can no longer remove water from the surface and the roots no longer have any air, if the roots sit in water for too long then the plant starts to die and you see the grass turning brown/yellow.
Now we are in October temperature are colder so it takes longer for the turf to dry out, the damaged caused now will not recover and will still be evident next spring.
The decision to close is not taken lightly and is always made in the best interests of the course.