In order to say "X is really important to achieve Y" you need to try things other than X.

So if you write a blog post about how hiring engineers who are a great fit is the most important thing. And one of the 'tests' you give them is to see if they select grapes or candy as a snack, then only hire people who eat the candy. You don't actually know that eating candy is important, it's the only thing you've done. You need to hire some grape eaters and see if anything changes.