The Ravens need a No. 2 running back to complement starter J.K. Dobbins in the early part of the regular season, and veteran Mike Davis got closer to filling that role with a strong effort in the team’s 23-10 win over the Tennessee Titans in the preseason opener Thursday night at M&T Bank Stadium. Throughout the first two weeks of training camp, the Ravens rotated Davis, fourth-year running back Justice Hill and rookie Tyler Badie in the starting lineup, but Davis appeared to separate himself from the pack against the Titans. There are two unpardonable sins for a running back in the Ravens’ offense: fumbling and failing to pass block.