Over years I've found that "top performer" is not purely about skill, often it is *just* about motivation, desire to move stuff ahead, to get things done, to improve current state of affair.
Like, rarely stuff is so hard that it requires some outstanding skills.
Similarly, if you're a web developer and your language doesn't even have integers, then understanding twos compliment is probably not fundamental.
That said, the people who proudly know the very least amount possible to perform their day job usually are not top performers.