The saying you are referencing above is not as literal as you are implying.
Not that specific and common, just sometimes I find or hear of, say, a football player for example, saying that being good or bad at football is equivalent to being good or bad at life.
This football player, following your example, is saying that the same basic elements of success are universal; therefore, similar drive, work ethic, dedication, study habits, etc that go into being good at football will work for anything else. If you worked as hard at writing as he did at being a quarterback (or whatever), then you would be able to write at the same level he plays football at. Keep in mind that this would mean writing, or doing something like studying grammar, for 4-8 hours a day for (probably) over 10 years.
I believe what Mizal is saying is just humor. That your writing potential is based on your "order," when in reality order is determined by something like the date you signed up...
Not sure why I am clarifying this, you probably already know this. I am easy to troll I guess.