What makes someone a 'good' Apex player?

Good players literally give no Fs about stats. They already know they are good.

Especially in a BR there are far too many things beyond a players control to use numbers as a reliable gauge.

There's quite a big difference for example between getting 2.9 knockdowns and actually getting 3 full knockdowns. Not everyone can 1v3 every single fight like Timmy, but that's what you will often need to do if you solo autofill.