I think it's a mistake to think that developer ability is static, "quality" isn't a constant thing, by any means. Certainly we're supposed to keep learning and progressing. But there are plateaus. For example, I don't think myself or the person I championed for the raise/promotion were exceptional, it was simply a situation where what we were doing really "clicked" with both of us.

Later on, I had a member assigned to the team. They were going to fire this person, but asked me if he could have a chance on our team. I said sure. Turned out that this person needed a bit more guidance than they had received before, and when they got it, really began to shine. This person went from almost being fired to being a really valuable contributor on our team.

Myself, I left that company long ago, looking back I think it was a high point of my career. Never before or since have I had that level engagement with the domain or company.