As a ball carrier, Northern Colorado running back Caden Meis is a hard man to tackle. DGD, he tells himself on the field. He’s written the letters on his cleats and on his fingers as a reminder since high school. DGD means “don’t go down.” No Bears back was harder to tackle late last season and into the spring than Meis, UNC coach Ed Lamb said. High praise for a player in a position demanding toughness and more than a little determination.