GAINESVILLE, FLORIDA — It was not clear before the game if touted true freshman quarterback DJ Lagway would play in the Florida Gators’ season opener vs. Miami at The Swamp. But when starter Graham Mertz sustained an injury while throwing an interception with 24 seconds left in the third quarter, that meant Lagway would get a shot. And he did with 14:44 on the clock in the fourth quarter. With Florida trailing 38-10, Lagway’s first play was a hand off to running back Treyaun Webb, who gained 2 yards. He was stopped for a 4-yard loss on second down, then followed that up with an incompletion on…