I think you hit the nail on the head here. What KF probably doesn't get enough credit for is the way he does make adjustments year-to-year based on the personnel, talent in certain areas, injuries, etc. Good example, the year that we were down to the sixth string running back and all Drew Tate did was throw the ball for the most part. And we won 9-10 games, IIRC.
I think the offense will be better this year and if it isn't, we'll suffer the consequences. But there is talent on this team and the coaching staff has shown the ability to find a way to win on most Saturdays, and that's the name of the game.
As for Brohm, I think he is a tremendous offensive mind. But while he has had some great wins (see Ohio State in 2018) and been a thorn in our side, he hasn't won big at Purdue. And that is in the lesser of the two B1G divisions. This could be a big year for them but they'll have to show it.