I'd be slightly more careful about making the claim you are making (though in your defense, nearly every person who makes a boastful post about their A/B testing is makes the same mistake). For starters, you are picking an incredibly noisy metric, taking the maximum observed conversion and the minimum observed conversion and then dividing them. To better illustrate this, I wrote a little test script to simulate what…
You make an important point. We obviously have a lot of testing and refining to do. Thank you for taking the time to investigate our claim :)