Link to substantiate that claim? Or are you just making it up as you go?
To substantiate this claim, I am going to use logic expressions and statements.
1st statement: I have got a genuine Apple battery from eBay seller.
Proof:
1. The external design of the battery is the same, compared to the broken battery,
that was inside the Macbook Pro that is currently possessed by me, before replacement.
2. The capacity and performance are the same as they were when the Macbook Pro,
that is currently possessed by me, and the battery inside it, were new.
Source: I. Intensive testing. II. Coconut Battery statistics.
3. The seller has a very high feedback rating, so the chance that he is fooling his customers is extremely low.
Source: I. Feedback rating data was taken from eBay.
II. By "very high", we mean "relatively high, compared to other eBay sellers".
III. If he was fooling his customers, his feedback rating wouldn't be "very high".
4. From 1. , 2. and 3., we can conclude the 1st statement.
2nd statement: The battery was produced by Apple battery factory in China.
Proof:
1. 1st statement states that the battery purchased by me is genuine.
That means, it was produced by Apple-authorized battery factory.
2. The Apple battery factory is situated in China.
Source: Both broken and new battery labels say "Designed in California. Made in China."
3. From 1. and 2., we can conclude the 2nd statement.
Final statement: The factory in China manufactures more batteries than Apple orders, to sell the extra batteries later as the replacement parts.
Proof:
1. 2nd statement states that this battery was produced by Apple battery factory in China.
That means, Apple orders the batteries from this factory.
2. It is not profitable for seller to buy the battery from Apple for $130 and then resell it for $60.
That means, the battery was not bought from Apple.
3. It is not profitable for seller to buy the Macbook Pro for $1800, remove the battery, and sell it for $60.
That means, the battery was not got from Apple laptop.
4. From 2. and 3., we can conclude that the battery, that I have got from eBay, is not included to the number of batteries that Apple orders. That means, the factory in China manufactures more batteries than Apple orders.
5. It is not profitable to manufacture more batteries than Apple orders, unless they are not going to be resold later.
6. Most customers will buy the batteries to use them as replacement parts.
That means, the batteries will be sold as replacement parts.
7. From 1., 4. and 6., we can conclude the Final statement.
Enough?