IOWA CITY, Iowa (AP) — Damon Bullock will step into perhaps the most treacherous position in college football on Saturday when he starts at running back for Iowa. The Hawkeyes just can’t seem to keep its tailbacks on the field. Iowa’s bad luck with backs reached a breaking point in the offseason. Five players expected to compete for carries in 2012 won’t be on the field Saturday when the Hawkeyes face Northern Illinois in Chicago. All that’s left is Bullock, a sophomore who also played receiver in 2011, and a pair of true freshman in Greg Garmon and walk-on Michael Malloy. Iowa coach Kirk Ferentz says Bullock had a good fall camp and that he’s been impressed by Garmon and Malloy.