1) the new system of selecting tickets (which is very modern for ND) ironically results in less demand, especially when they overprice the games that use to be, at best, fall back lottery options. For example, knowing the demand for games like Georgia and USC would be high, we used to order tickets for a back-up game or two just to be able to go to a game. This year, we knew that we were getting Georgia and USC games so we didn't have to order those games. In the past, had we won the big games, the extra unwanted tickets who go to relatives/friends/neighbors/co-workers usually at less than face value. Now we don't have to worry about that. Hence we bought less tickets but will go to the same amount of games we would have gone to anyway.
2) they really overestimated how much people would spend a full day to sit in shitty seats for shitty games, some in November. I think most people seem to think spending even $45 to sit high in the end zone to watch Navy or Wake Forest isn't worth that. Heck it isn't even worth $75 to sit in the corners for games like that. And, if they do as they say they will, ticket practices will stay the same for 2018, games like Ball State and Syracuse will be only 75% full.
3) They seem to think that the new stadium with "enhanced" experiences will attract buyers when few people think ND has the ability to effectively and interestingly make use of all the bells and whistles of their new toys when they couldn't cope with what they used to have. No one expects to get any level of professional announcing warranted by their pricing as opposed to some athletic department apparatchik who has been doing an inept job for years as they announce the score of the Michigan v. North Southwestern State(56-5 by the way) on end well into the 4th quarter.
On top of all that, these communication/marketing geniuses have put themselves in the realm of main stream media level of fake news when they already are chalking it off to "lower demand in general" for live events like college football games as opposed to their arrogant ill-conceived pricing strategies which they say will also hold for 2018.
All in all, we shall see what kind of "explanations" (aka excuses) they offer for the scads of empty seats we see for the 5 PM Miami (OH) game this year.