Yes and I addressed this. If you are a Nascar driver, you can confidently say that you are a better than average driver.
If enough companies have been willing to hire you as a lead developer or an architect and you haven't gotten fired, you can can say with some confidence that you are better than average.
Definitely its context. I stayed at one company 7 years longer than I should have and then started being more aggressive about my career in 2008. I was an average to slightly below average developer from 2009-2016. I chose jobs that between my interview skills and technical skills, I knew just enough to get into the door, learned all I could from people who were much better than I was and once my skill set outpaced the salary they were willing to give me, i left for another job.
Now, after being a journeyman for the 9 years, I'm the tech lead for a small development shop. I consider myself the top performer because what I do has the biggest development impact on the company.
I did agree it was contextual whether you are a top performer within your peer group (in my case, I'm the developer lead for the company). But we don't just compete for jobs in the company you work for now, you compete in the entire market. How you define your market is based on location and willingness to relocate.
If enough companies have been willing to hire you as a lead developer or an architect and you haven't gotten fired, you can can say with some confidence that you are better than average.