It's not often that a mid-round draft pick enters the immediate conversation as a potential Offensive Rookie of the Year candidate, but that could be the case for Denver Broncos running back Jonah Coleman . NFL Draft On SI 's Justin Melo put Coleman firmly in the ORoY conversation after the Broncos drafted him in the fourth round. " The Broncos finished 16th in rushing last season. That's fairly disappointing considering dual-threat quarterback Bo Nix averaged more than 20 rushing yards per game. The challenge here for Coleman is how crowded the position room is. J.K. Dobbins was re-signed this offseason, and last year's second-round pick RJ Harvey should continue developing. If injuries or performance issues push Coleman up the depth chart, he has a pro-ready, three-down skill set to take advantage ," Melo wrote. And that's the rub. Coleman is going to see the field as a rookie no matter what happens ahead of him as the depth chart because he's such a powerful and productive runner between the tackles.…