Brohm has beaten KF both times they've faced each other, home and away. Both games were completely dictated by Purdue and how they wanted to play. Purdue has equal or lesser talent than Iowa on their team. That's coaching.
KF has bested Harbaugh one time, at home, at night. Can't take anything away from that. Paul Chryst is a good coach, but also has more talent on his roster than Iowa. So it's tough to say he's for sure better than KF.
It seems to me like you're determining based solely on legacy numbers. That doesn't really make much sense at all. Just because KF has been around longer doesn't make him a better coach at this time. That's like saying Andy Dalton is a better QB than Patrick Mahomes because Dalton has more career wins.
Jeff Brohm is a 6-6 coach. He got blown out by row your boat and lost to E Michigan. He eeked out a win against Indiana to go to the Car Care Bowl probably. Let me know when he accomplishes something.