The last time the Denver Broncos had a layer named NFL Defensive Rookie of the Year was in 1991 when linebacker Mike Croel, the No. 4 overall pick out of Nebraska, won it. He recorded 10 sacks as a Broncos rookie. Von Miller, the No. 2 overall pick in 2011, is the front-runner for the award, having 10.5 sacks through the first 12 games of the season. He missed last Sunday’s game with an injured thumb, but he appears ready to play against the Chicago Bears.If he has an actual competitor for the award, it is the San Francisco 49ers’ Aldon Smith, who has 9.5 sacks so far this season. As ESPN’s Mike Sando points out, Smith actually has a better sacks per play average, but that’s only because Smith plays on passing downs. Miller plays against the run as well, providing him with over 300 more game situations.Plus, Miller is already one of the team leaders on defense for the Broncos. Smith isn’t quite there yet. Miller won’t quite be a unanimous selection for defensive rookie of the year, but he won’t need to sweat out the results when they are revealed.For more on the Broncos, visit Mile High Report. Be sure to check out SB Nation NFL for more on the league.