AMES, Iowa (AP) – This fall was always supposed to be when Jerome Tiller took over as Iowa State’s quarterback.  The redshirt junior spent the past two seasons serving as Austen Arnaud’s understudy, soaking up the lessons offered by one of the program’s top quarterbacks.  But Tiller might only have another two weeks to prove he’s ready to be Arnaud’s successor.  The Cyclones have thrown the starting job up for grabs, and Tiller’s just one of three guys fighting for the chance to grab it.  Tiller says improving his accuracy is a focal point in his efforts to beat out Steele Jantz and Jared Barnett for the top spot.