People still talk about "A9" optimization. But A9 is dead. We are living in the A10 era, where off-Amazon traffic is king.
1. The Legacy A9 Model
A9 was simple: Sales Velocity + Keyword Relevance = Rank. If you bought PPC sales, you ranked organically.
2. The New A10 Model
A10 changed the weighting. PPC sales count for less organic juice than they used to.
- Organic Sales: 10/10 Impact
- External Traffic Sales: 8/10 Impact (The "Halo" Bonus)
- PPC Sales: 3/10 Impact
This means you cannot just "buy" your way to the top with Amazon ads anymore. You need a brand.