https://www.profootballfocus.com/pro-ranking-all-32-nfl-running-back-units/ ....2. Tampa Bay BuccaneersStarter: Doug MartinBackup: Charles SimsKey stat: Doug Martin and Charles Sims both earned top-five marks among RBs in elusive rating last season.Martin ended last season with the highest rushing grade among all NFL running backs, but the problem is we can’t always be sure how long his high levels will last. Martin has two stud seasons on his résumé alongside two duds, and it seems like any sort of injury seriously hampers Martin’s game-breaking ability. Even if Martin does falter, though, Charles Sims has proven that he has the ability to be a featured back in this league. Sims is already arguably the top third-down back in the NFL, and earned the fourth-highest receiving grade at the position last season....