If the Michigan State game is any indication of Brian being a top flight OLine coach, I'd say he still has some learning to do. Not every Iowa offensive lineman is going to be a high draft pick in the NFL if they were to graduate today. Brian needs to learn how to compensate for linemen that may be deficient due to injury, ability, 'rookiness', whatever in game day situations.
This is how Brian becomes a top flight OC or head coach: By mastering all the position(s). After he's mastered the OLine position, make him the running backs coordinator. Then the QBs coordinator, etc. When he's mastered all the coaching positions of the offense, he'll be ready to be an OC. Then make him DLine coordinator. LBs coordinator, etc. When he's mastered all the coaching positions of the defense, he'll be ready to be DC. When he's mastered both OC and DC, he'll be ready for a head coaching job. Notice I've left out the mastery of special teams. Maybe he'll need to dabble, there, too.
Being master of every position doesn't mean the head coach contributes to every position or even attains veto power for every position. At least when there is some sort of impasse on the team you, as masterful HC, can provide leadership with lots of clues for the situation.
Besides, I know this thread has turned out to be a backhanded critique of Greg Davis' ability and not so much a herald of Brian Ferentz's ability.