Apparently, Northwestern coach Pat Fitzgerald isn't a fan off topsy-turvy amusement park rides.

"I think if you get up on that roller coaster, man, that's why some people get sick going up and down," Fitzgerald said earlier this week, speaking of his undefeated team's upcoming game at Purdue. "You just can't do that. You've got to be consistent."

Funny, considering no other team in the Big Ten has had a more wild ride in recent history than the Wildcats.

Northwestern topped the West division in 2018 with an 8-1 conference record, followed that up with a rock-bottom 1-8 division finish in 2019 and has currently regained its No. 1 spot at 3-0 in 2020.

Actually, draw Northwestern's trajectory in the Fitzgerald era on a piece of paper, and the results since 2006 resemble exactly what Fitzgerald tried to warn against: a slow climb to the highest peak, a stomach-turning sheer drop and a skyrocket back to the pinnacle.

Not exactly the stability the coach was calling for, but certainly a thrill.

The 2018 success came partly from fourth-year starting quarterback Clayton Thorson and his 3,183 passing yards, 17 touchdown passes and nine rushing scores. The school's all-time leading passer sent the team to the Big Ten championship game, where whichever West team goes is essentially the sacrificial lamb to Ohio State, and on to a Holiday Bowl victory.

The offense very much was not the Wildcats' strong suit in 2019. In fact, it was a liability. It averaged just 16.3 points and 297.1 yards per game. Northwestern cycled through four different starting quarterbacks, and none of them could generate any sort of production, even former five-star recruit and Clemson transfer Hunter Johnson.

So when former Indiana quarterback Peyton Ramsey transferred to Northwestern for his last year of eligibility in 2020, there was some healthy skepticism. But his offense is already an improvement from last season, gaining about 375.7 yards and 28.3 points per game.

The real Wildcats highlight for 2020, though, is its defense. It allows opponents just 12 points and 314 yards per game, behind only one-game Wisconsin in the Big Ten. The defense hasn't allowed any second-half points this year and sports impact players such as linebackers Blake Gallagher, Paddy Fisher and Chris Bergin, who lead the team in tackles with a combined 84. And that's not even taking into accounts the sacks, interceptions, pass breakups and quarterback pressures the trio also contributes.

This Northwestern team has all the makings of another West champion, having already dispatched Maryland, Iowa and Nebraska. Left on the schedule are Purdue, Wisconsin, Michigan State, the Gophers and Illinois. Those next two games are against currently perfect-record teams, though both had games canceled because of COVID-19. The latter half of the schedule doesn't appear to be a huge threat this year.

A rematch of the 2018 game for the Big Ten title against the Buckeyes, though, could be a doomed repeat of the past.

For now, Northwestern can enjoy its view from the top — and hope there's no drop-off just beyond the horizon.

"Well, we've won," Fitzgerald said of his season so far. "So that's all the matters."

megan.ryan@startribune.com

@theothermegryan