The birdbaths are typically seen after a rain or after having your court cleaned. Mark the areas and take a photo showing the relative position to the court lines. Have the low areas filled prior to resurfacing your courts. A mixture of Portland cement, silica sand 40 mesh, and acrylic patch binder. Mix the cement and sand (6 bags sand to 1 cement) together first, then add the acrylic patch binder. Mix to a thick consistency. Spread over the low area with a straight edge or stiff squeegee. Flatten the edges down with the toe of your shoe or a trowel. The smoother the edges are the more manageable the final sanding will be.
After leveling the birdbath, a coat of resurfacing material will be applied.
Filling larger cracks with asphalt helps mitigate the crack from returning larger than before. This is due to the same or similar product being used on your court surface. The same product expands and contracts at the same rate as the existing court. When a cement mix is used you have unlike materials pressing or expanding and the cracks can become more prominent over time.
This shows the birdbaths filled with water. Always a hassle to squeegee off or blow out with a blower. Startup companies might use asphalt contractors that are experienced in laying asphalt on roads or parking lots but not on tennis courts. The gravel base must be level for the asphalt to be level. Currently, the experienced contractors use a laser level for the gravel base to ensure the asphalt is level. Part of the contract should have the court flooded with water and let it dry for an hour. If there are low areas filled with water that are deeper than a nickel, they should use the cement acrylic patch binder mix to level it out prior to resurfacing the court