I believe that the top trait in A players is the same as in the top founders, which is determination [1]. That determination often manifests itself as the desire to understand how something really works, rather than glossing over the details, the drive to learn a new language well enough to use it to implement ideas, to take on the learning curve for a new tool or system, to automate something, or to test their code before releasing it into the wild.

I've seen less-than-enthusiastic programmers who release shoddy work, expend more effort moving work onto other's plates that they'd expend just doing it themselves, let bad ideas stand without a fight, and never bother to keep up with changes in technology.

I've also seen very smart developers who've constantly been taken in by the latest shiny new thing to cross their path, think that testing is for the weak, and have no real determination to get something up and running completely.

If I have to be honest, I would describe very few of the developers I've worked with as "dumb". But many of them are either too passive [2], or lack the determination or desire to really compete a project.

One thing I've done to grow is to not try very hard to gloss over the details. Software is supposed to abstract away details, but it's too easy to think "I'll never learn that." or "Who cares what's under the covers? It just works." Understanding the subtleties isn't just an intellectual pursuit. Knowing the internals of a system allows a developer to know the limitations and strengths of a system, so it can be built upon or even repaired and improved.

1. http://paulgraham.com/determination.html 2. Sadly, in some situations, these are people who've simply been overwhelmed by the bureaucracy of their workplace. Fortunately, we are currently in a job seeker's market, and determined people can find better work conditions.