The Minnesota Vikings’ season was effectively over before my Christmas tree came down. The state’s sports journalists are donning their gloves and sharpening their scalpels, preparing to conduct the annual autopsy. The Vikings suffered from some negative exogenous shocks, to be sure, primarily the loss of quarterback Kirk Cousins. But such persistent failure suggests a persistent malady. Two pieces of research suggest that the Gopher State’s high taxes might be a factor.  In a 2018 paper titled ‘Touchdowns, Sacks and...