People forget that in addition to just flat out running over top of people and running the option with Rice, ND also threw a ton of quick outs to WRs during games -- and we had people like Brown, Waters, and Rocket catching those 1 yard passes. He also would throw a few bombs per game.
His passing was very strategic to try and prevent teams from completely stacking the box against the run -- and his rushing design also forced teams to defend sideline to sideline every play because there was a threat of a naked bootleg, the pitch to either side, misdirection, etc.
Kelly's passing game -- Chip -- factors a lot of those same concepts in. He just makes passing the primary focus with the run the complimentary one. Brian Kelly is missing half of the dimensions of either of those coaches in terms of forcing teams to defend the entire field.