I am still not sure what of Mess's resume suggests there are not dozens of better candidates. He had no previous experience running this type of offense, and his only time in this offense was over the previous poor 3 seasons under Herman. He had little, if any, as being an OC at an FBS level. Hell, he had relatively little experience calling plays period.
Save your Herman at OSU fallacy. First, Herman is Urban's towel boy. Second, if you need Ohio State talent to avoiding being bad, you have the wrong scheme. This offense does not minimize or hide talent disparity at ISU, it magnifies it. Herman's offense at ISU was not a good fit (without superior talent it is average at best), but at least he was familiar with his own offense.