Machine-made so little variation or imperfections, a much flatter seam, and goes soft more quickly, meaning it's a lot less friendly to English seam bowlers and conditions, and when it ages it becomes lifeless. This was supposed to get seamers prepared for Australia and promote spin. Except they don't release test match bowlers to the Championship anyway, meaning that all it did was make average bowlers look terrible and average batsmen look like Bradman.