I don't think the graph is still relevant, in 2017 most projects are ERC-20 tokens, that's why the money flowing in ETH since the project need to have gas fees. But nowadays, most people don't like ERC-20 tokens anymore due to high fees, it moved to BSC and now it moved to SOL.
But it's only outperform in that time.
I don't understand what you actually meant by ETH outperforming Bitcoin when we know that Bitcoin dominance of the market is still above 51% while ETH has 16%. There's still a huge gap.
I think he meant if ETH price increased higher than Bitcoin price in terms of percentage, ETH outperform BTC. But it's only outperform in that time.