Quarterback controversies are rarely straightforward under Brian Kelly at Notre Dame, but Ian Book's arm gives the Irish the better chance to reach their ceiling.

Brian Kelly’s decision to make a change at quarterback might have changed the trajectory of Notre Dame’s entire season.

Making his second career start for the Fighting Irish against Wake Forest last Saturday, Ian Book completed 25 of 34 passes to 10 different players for 325 yards with two touchdowns and ran for three more. He led an offense that had topped out at 24 points this season under initial starter Brandon Wimbush to eight touchdowns and 566 total yards in a lopsided 56–27 road win over Wake Forest.

“I was really confident,” Book said after the game. “Obviously I had a little nerves from the first couple plays, I haven’t been out there the whole game in a while. It felt good though.”

Wimbush is a remarkable 12–3 as a starter for the Fighting Irish, though he has never passed for 300 yards in a game. Last year, he relied on his feet to win games and struggled to be a consistent passer. When he broke the Notre Dame career rushing record for a quarterback last fall, his reaction was to ask who held the school’s all-time passing record because that was his goal. His inefficiency through the air wasn’t due to a lack of hard work. This offseason Wimbush sought out a skills coach on the West Coast for help with his mechanics and spent extra hours honing his relationship with offensive coordinator Chip Long. He’s a smart player working toward a degree from Notre Dame’s business school, who had an internship last summer at a venture capital firm in Silicon Valley.

But despite all that preparation, he hasn’t shown enough improvement. As it stands heading into the fifth week of the season, his quarterback efficiency rating of 114.17 doesn’t rank among the top 100 QBs in the Football Bowl Subdivision.

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Therein lies the bold and necessary change Kelly had to make if this team was going to make a run at the College Football Playoff. The Monday before Notre Dame played Wake Forest, Wimbush and Book’s practice reps were split 50-50 instead of the usual 60-40. That was a hint of what was coming.

“We weren’t winning at a level that was going to allow us to continue to win,” Kelly said after the win over Wake Forest. “We were putting too much stress on other parts of the operation, particularly the defense. We played 97 snaps against Ball State. It was going to break. So it needed to get fixed now.

“It had nothing to do with Brandon in particular as much as how the offense needed to be much more effective. That’s it.”

Book has often risen to the occasion for Notre Dame. In his lone start of 2017, he led the Irish to 33–10 win over North Carolina while Wimbush was out with an injury. Then he came on in relief of Wimbush during the Citrus Bowl and beat LSU. Now he figures to be the starter moving forward, though Kelly is reluctant to say as much. The Notre Dame coach has reiterated that both quarterbacks are capable of winning and both will continue to prepare. Perhaps it’s because this is a difficult situation all around given how much the coaches respect Wimbush. Kelly said he “didn’t sleep great” the night before the Wake Forest game.

Having both quarterbacks ready at all times isn’t the worst idea, though. Kelly has used a two-quarterback system several times before. In 2012, the dynamic between Everett Golson and Tommy Rees was productive; in 2016 the competition between Malik Zaire and DeShone Kizer was more toxic. Wimbush and Book are close friends and outwardly say they just want what’s best for the team to win.

Wimbush and Book battled for this starting job through the spring and summer. Once fall camp began, Wimbush had seemingly done enough to earn his spot back, and Notre Dame began preparing for Michigan with him in mind. Wimbush led scoring drives on three of Notre Dame’s first four possessions of the season to take a quick 21–3 lead on the Wolverines. Those plays were scripted, and Wimbush had a month to prepare and memorize his moves, which he executed perfectly. But when it came to making in-game adjustments or moving forward in the game plan, he struggled. Michigan held the Irish offense to just 69 total yards and five first downs in the second half as Notre Dame held on for a 24–17 win. Wimbush has shown limitations in adapting on the fly, while Book is more natural in that setting.

“We needed Brandon against Michigan because of Michigan’s defense,” Kelly said. “The whole off-season was focused on Brandon beating Michigan. [Running backs] Jafar Armstrong and Tony Jones were not ready. [Wide receiver] Kevin Austin was not ready. Our leading receiver [Miles Boykin] I think had nine receptions coming in. The offense was not mature enough going into Michigan.

“The playmaker on our offense was Brandon Wimbush. It needed to center around him to beat Michigan. And then the next two weeks, those kids needed to mature and then we needed to make this decision that we did relative to the quarterback position.”

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If No. 8 Notre Dame beats No. 7 Stanford on Saturday, it has a realistic chance of going undefeated in the regular season. After facing the rival Cardinal, the schedule looks like this: at Virginia Tech (a matchup that lost some hype after the Hokies were stunned by Old Dominion and lost quarterback Josh Jackson to injury), Pittsburgh, Navy (in San Diego), at Northwestern, Florida State, Syracuse (at Yankee Stadium) and at USC.

Bottom line: if the Irish make it through the weekend, the College Football Playoff is a realistic goal.

Kelly can keep saying that both quarterbacks are going to prepare and both need to be engaged and ready to play. But it’s Book, a former three-star prospect whose only other offers were from Washington State, Boise State, UNLV and Idaho, who must control the offense moving forward.

“I came here to be a starter, and it’s up to the coaches, and they’ll play the best quarterback to win,” Book said. “We’re all one team and I’m not worried. I know they’ll make the right decision, whatever that is, both ways. We’re here to get wins.”