Can I pick on myself in the course of larger picking on the cult of "A players"?
I'd rate myself as C- at my first job, local-A-but-global-C at the salaryman gig, A at Bingo Card Creator, C- at Appointment Reminder, A+ to B- depending on engagement during my consulting career. (I'll take the liberty of excluding my last two gigs out of social concern.)
I am something of an expert on my own work history and can pull any amount of evidence required to substantiate these lower grades. I literally slept on the job as a translator, out of boredom and underengagement. That should be classic C behavior, right? I think I missed growth goals (that I set and owned!) for ~20 consecutive quarters at Appointment Reminder.
And yeah, I also have done some pretty good work over the last 15 years, too.
So what happened? Some of it was straight-up skills growth; I'd paste 25 year old me along almost any axis (10 years later). But 25 year old me had approximately the same health, approximately the same intelligence, and approximately the same diligence... how come he couldn't figure out what time to leave the house to reliably arrive at 9 AM, even though he knew his colleagues were exasperated by that?
Part of it is the nature of the organization. If you're a 26 year old at a Japanese megacorp if you give what is, to the global standard, excellent work, the company's immune system will reject you. I was a good soldier, and gave the organization what it wanted, which is (by the standards of almost any HNer) shockingly low measurable productivity, delivered in a fashion which suggested that I was going to upset no apple carts. I don't know if there is any company routinely present on HN which is not a Japanese megacorp that would be even borderline happy with me reprising that performance.
I strongly believe that there are ways to be an excellent A+++ Googler and replicate the same performance at a startup while flying it into the side of a mountain, at an angle and speed which non-Googlers would be envious of but for the whole flaming death thing. This goes for many tuples which are not (Google, archetypical startup), too.
There are a number of factors other that identity-of-organization that are also confounders. I think I have highly variable productivity (even if you drop periods of poor health as outliers), and if consistency matters to you more than absolute results, I would be a poor candidate for most jobs. I have had team dynamics which acted as force-multipliers for me (and vice versa); I have had teams which had dynamics where adding me added much less than a simple "sum the productivity of these two units" model would suggest.
I think that I'm much, much better at some roles than I am at others. I'm a passable interpreter on my best day and have had serious breaches of the canon of professional ethics twice. (The canon is wrong on the issue [+], but it isn't ambiguous.) I'm a much better writer... in English, on a restricted subset of topics, to a particular audience/cluster of audiences.
I do not think that my written work is a complete accounting of what I'm good at; I think my median reader probably underestimates my technical ability substantially (for plenty of good reasons, median reader) and probably substantially overestimates... hmm... sales ability. (I'm pretty good at sales, but people probably give me too much credit. I frequently fail to do table-stakes things like aggressively following up to make sure indications of strong interest turn into signed contracts ASAP.)
I endorse using samples of written work as likely indicators of ability, but I don't think the static caste system model of A/B/C players cleaves reality at the joints, and accordingly I don't think that written work likely helpfully buckets people as A/B/C.
[ + ] To forestall the follow-up question, the issue is "Translators/interpreters MUST reproduce the input as closely as they are capable of in the output [even if the input is monstrous or the correct output would contravene other goals of the translator/interpreter]."