This story struck me as a decent report of a researcher's statistical work. The strength of the logical connection—a feature that's too often weak in statistical studies—seemed reasonably well-covered, too. But in general I'm skeptical of single-factor explanations for such complex issues as a pandemic, and the data seems mostly anecdotal. We have huge variances here in the US, for example, but I haven't seen any data about the prevalence of mask-wearing in different cities or states; I'd like to see the data discussed more in depth