Jim,
Again, not specific to what Philly did, but its typical to remove existing turf, which usually removes at least a few inches of roots, etc. and they need to put that few inches of mix back in, perhaps rototilling together with the substrata if that isn't the same type of sand.
Tough question about what to do if they still had old push up soil greens. When sodding greens, you typically try to find a grower with the same soil you have. In many areas, a sod guy will do this for many clubs. Short version - it can be a bit more complicated than just killing grass and laying sod.
Will be interesting to hear what they had/have.