Basically, the criticisms I've seen of him lately seem to based on the idea that Silver is failing to sufficiently emphasize the positives that made him valuable (focus on methodology, empiricism, contingency-based thinking).
It's not simply that. It's also that he's using dubious statistical methods
in the pursuit of a political agenda, namely Silver's personal antipathy toward Trump and bias toward Rubio that he's expressed on multiple occasions, when he had previously been more or less "objective" in his application. It's not that he's diluted, it's that he's violating the "Do No Evil" principle in applied statistics.