I've only had two boosts and no best writer nods. One boost made little to no difference. Another really took off – that month, I made almost $75 – my highest monthly earnings to that point. I also found it stifling creatively to try to pursue them.
I don't know why further writing isn't gaining that kind of attention. As you pointed out of your own, my writing quality nor quantity have diminished. In fact, my quantity of writing has increased. I'm also getting much wider distribution in the past few months. But, I didn't see an increase (excepting that big boost story's month) in my Medium income until the new system began last month. I averaged around $40 to $50 a month. Last month, I surpassed $170.
I remain pleased to make more than the annual fee, though. That's really all I ever expected. I love the connection here. And, that the majority of those connections feel like the best of us (as in humanity). So many fewer trolls and detractors than other social media venues.