With support from George Kittle, T.J. Hockenson and Hall of Famer Jared Allen, a new pro league for the winter pastime is working to engage fans beyond the Olympics.Just a few miles from the buzz of Nashville’s Broadway strip, past the honky-tonks and pedal taverns, sit four curling sheets inside a warehouse-like building called Tee Line. There, current and former NFL players George Kittle, T.J. Hockenson and Jared Allen are pushing the roaring game of curling into a new era. Through the NFL offseason, and more often for the retired Allen, a Pro Football Hall of Famer, they swap...