It looks like the only thing that could have been delayed is pouring the last of the top rows and the remaining transition pour between the old and new. The forming is not finished, but few are working on a perfect day in Berzerkeley.
Excavated dirt from lowering the field cannot be transported wet.
I've worked a few remediation projects and we hauled 'wet' dirt all the time to hazardous waste disposal sites.
The real problem is that 'wet' dirt weighs more than 'dry' dirt and it is easy to overload the trailers. The result is more loads to remove the same volume of dirt; > greater trucking cost. And it is messy. No need to work the muck if you can schedule around it.