You will always get some cratering in the grounds basket, and dimpling as well, because the water is coming through drip holes. The grounds bed will rarely ever be flat like a manual pour-over, because that allows people to manually manipulate the water. The grounds basket will vary in appearance for grind size, type of grinder used (an uneven grind can skew the grounds bed), amount of coffee, coffee type, roast level. which also dictates cup quality. If you are concerned the cratering is excessive, here are a few things to look at:

• Did you level the grounds by tapping sides before starting?
• Did you look at the basket well after brew cycle so the leftover condensation creates the collapsed area, or immediately after?
• Can you check to verify that your table or countertop is level? Gravity has a lot to do with the water flow through all drip machine showerheads. If unlevel, the water will not flow properly to all grounds. If you find it is not level, you can adjust the rubber plugs on the bottom of the brewer.