First of all, during the offseason NDSU hired a new offensive coordinator (Brent Vigen) and defensive coordinator (Mike Breske). It will be the same systems on both sides of the ball but the play calling may be a little different.
Second off, NDSU lost a ton of seniors that were the backbone of NDSU for the last 4 years., the top ones being Ramon Humber (LB), Mike Maresh (LB) , Tyler Roehl (RB), and Kole Heckendorf (WR). Heckendorf is only the greatest WR to ever play at NDSU. Ramon Humber (In NFL now) and Mike Maresh were both good for 100 tackles/yr. Tyler Roehl (RB/FB) had two 1000 yard seasons in a row (he is the one who ran for over 200 against the gophers). You combine all of those losses with about 6 or so current players being kicked off the team for academics/legal infractions, and you lose alot of experience.
As long as we dont turn the ball over all night, I dont see NDSU beating ISU, but thats why they play the game.