Notre Dame will have a (slightly?) tougher time with FSU due to Ian Book’s absence

As new CFP No. 3 Notre Dame prepares to host Florida State, starting quarterback Ian Book will miss the game due to midsection injuries.

Book took over for incumbent starter Brandon Wimbush after Week 3, sparking some significant overall improvement by the Irish. Going by S&P+’s offensive percentile performance rating, the Irish had two poor showings in their first three games of the year, but only one (Pitt) in the six Book has started.

The Irish would go back to Wimbush against the Seminoles, against whom they’re favored by 18 and have been picked to cover. Wimbush isn’t a bad player and made some great plays in 2017, but this is obviously a blow for the Irish.

As Bill Connelly writes:

Through three games, Notre Dame was 3-0 but underwhelming. The Fighting Irish had 24 points against Michigan, which is impressive, but they managed just 24 and 22 against Ball State and Vanderbilt. With Brandon Wimbush behind center, the Irish offense seemed to have a firm ceiling. So Brian Kelly promoted Ian Book.

Notre Dame’s S&P+ rating if it had only played the first three games: plus-12.3, 20th overall. The Irish are third in Def. S&P+ in these games but a ghastly 88th on offense.

Notre Dame’s S&P+ rating if it had only played the last six games: plus-23.8, sixth overall and hundredths of a point behind fifth-place Georgia. The defense remains third, but the offense is now 16th.

Notre Dame’s Off. S&P+ rating with Book is 38.3 adjusted points per game; with Wimbush, it’s 26.4.

Again, we’re dealing with perpetually small sample sizes here, but this could keep Saturday’s Florida State-ND game within a couple of touchdowns. The Irish are projected to win by 22.9, but that includes a half-season with Book.

There are some significant differences in comparing Book to Wimbush.

For one, accuracy. While completion percentage is not a perfect barometer of accuracy, Book literally leads the nation in completion percentage against FBS teams at 74.5 percent. Wimbush, on the other hand, is at 55.3 percent, which ranks 93rd nationally according to cfbstats.com.

Book’s Marginal efficiency is 13.3 percent, while Wimbush’s is just 3.0. And despite being a little less athletic than Wimbush, Book is sacked about half as often (3.8 percent to 7.3).

As a runner, the two QBs have been roughly even. Book has a higher yards/carry number at 4.8 to 4.1, but Wimbush has a slightly better marginal efficiency rate at -3.5 to -3.7.

Still, it’s just FSU, a team unlikely to make a bowl and unlikely to score many points on Notre Dame. The Irish are still favored by 16 points.