I was at that game at Arrowhead. I knew our offense was bad but I didn't remember it being THAT bad.
Not trying to take anything away from Buddy because he was a top notch defensive coordinator but we also only had 141 yards rushing (on 44 attempts, a paltry 3.2 ypa) the next week in a loss to Texas A&M as well. So it's possible that the Washington game was the out-lier instead of the reverse.
Perhaps Frank just wasn't cut out to be an offensive coordinator.
/crawls in foxhole
Considering the TAMU game was after the OSU game, it's more likely that they saw the film and adjusted to a similar defense that they saw OSU have work for them. Washington was 6-6 to finish that year so I'm very sure it was a bit of both.
NU averaged 5 yards per carry (3050 yards total, would be good for 17th in the country in 2015) and also didn't have a 1000 yard rusher. Heck, didn't even have an 800 yard rusher (Buckhalter had 799). Nebraska scored 32 points a game and gave up 15 a game. Plenty of offense to win. The offense just seemed bad because of the video game numbers NU put up in Tom's last few years.
But I wouldn't call that 98 offense "Bad"