Grading and compaction of subgrade materials are very important for the outcome of how smooth the ball rolls. Drainage materials consist of clean rock and sand. I recommend using limestone chat, decomposed granite, or any imported materials that have permeable qualities.
When the grading is complete, the underlying surface should be equally smooth without any compactor lines or small holes. If the subgrade materials are not smooth, the golfer will complain about irregular “ball roll”. It is especially important that the area around the putting green cup be consistent.
If you are going to use type II or road base as your grading materials, I recommend placing 1 inch of chat or decomposed granite on top and compact to complete a smooth surface. Type II and road base has too much aggregate (rock) and will cause problems with proper “ball roll”.