Analysis: How USC's defensive game plan impacted Notre Dame's passing game

USC didn’t want Ian Book to get too comfortable Saturday night in the Los Angeles Memorial Coliseum. The Trojans made a concerted effort to put pressure on Notre Dame’s quarterback, force him into early throws and dared the Irish wide receivers to create separation.

The planned work at times during No. 3 ND's eventual 24-17 victory in the regular-season finale for both teams. It backfired at others. That will likely to be the defensive blueprint the Irish offense will see in the College Football Playoff. But those defenses shouldn't have to rely on blitzing as much as USC did.

The Trojans chose to send a five-man pass rush on half of Book’s dropbacks. Nine of USC’s 13 pressures came when the defense utilized more than four pass rushers.

The pressure affected Book. Against all pressures, he completed only four of his 10 passes for 72 yards and one touchdown with one interception against pressure. His other incompletions came on one bad throw, one overthrow, one underthrow and two throwaways. Book was also sacked twice and scrambled once for a net of one yard rushing.

What other numbers tell the story of Notre Dame’s passing game against USC? Here’s a closer look.

• The different blitzes and pass-rush combinations caused problems for the Irish pass protection. Of the 14 different defenders who created pressure on 13 Book dropbacks, eight of them went unblocked. The rest of the losses to pressure were spread evenly, with one each for left tackle Liam Eichenberg, right guard Tommy Kraemer, left guard Aaron Banks, center Sam Mustipher and running back Tony Jones Jr. Book also ran himself into one pressure.

• Even though USC used a five-man rush more than any other quantity, it pressured Book at a higher rate using a four-man and six-man rush. Here’s how Book and the Irish offense fared against each pass rush quantity.

Three-man rush (3 times): 3-of-3 for 69 yards.

Four-man rush (12 times): 4-of-10 for 60 yards with one interception, two pass breakups, one throwaway, one overthrow and one drop. Book was sacked once and ran once for a net of nine yards. USC generated four pressures with a four-man rush.

Five-man rush (21 times): 12-of-21 for 169 yards and one touchdown with three overthrows, two pass breakups, one bad throw, one underthrow and one 50-50 throw. USC generated five pressures with a five-man rush.

Six-man rush (7 times): 3-of-5 for 54 yards and one touchdown with one bad throw and one overthrow. Book and wide receiver Chris Finke — on a clear gadget play — were each sacked once. USC generated four pressures with a six-man rush.

• More than half of USC’s pressures came when Notre Dame’s pass protection was even or outnumbered by the Trojan defenders. When the numbers were even on 10 dropbacks, Book completed six of his nine passes for 54 yards with one bad throw, one overthrow and one throwaway. Finke was sacked when Notre Dame tried a trick play. USC managed six pressures on those 10 dropbacks.

The Irish were outnumbered just once, and it ended with Jones scoring the game-sealing, 51-yard touchdown. USC brought six pass rushers and an unblocked Abdul-Malik McClain put pressure in Book’s face, but Jones was wide open for the long catch and run.

• The pressure rate of 30.2 percent registered the fifth-worst of the season for Notre Dame’s pass protection behind Michigan (56.3), Ball State (52.6), Pittsburgh (37) and Vanderbilt (35.5).

• Notre Dame’s passing game was spread out pretty evenly in terms of throwing depth, with Book once again struggling with accuracy on throws more than 20 yards beyond the line of scrimmage.

Book finished 22-of-39 passing for 352 yards and two touchdowns with one interception. Here’s how those numbers came together in terms of throwing depth.

Behind or up to the line of scrimmage: 6-of-7 for 65 yards with one drop.

1-5 yards: 6-of-7 for 96 yards and one touchdown with one pass breakup.

6-10 yards: 3-of-7 for 28 yards with one bad throw, one overthrow, one 50-50 throw and one throwaway.

11-15 yards: 3-of-7 for 58 yards with one bad throw, one pass breakup, one underthrow and one throwaway.

16-20 yards: 2-of-2 for 43 yards.

21-30 yards: 1-of-7 for a 24-yard touchdown and one interception with three overthrows and two pass breakups.

31-plus yards: 1-of-2 for 38 yards with one overthrow.

• More than half of Book’s passing yardage came from yards after the catch. His completions came at a depth of 164 yards, with 188 yards after the catch. The screen game only accounted for 60 of those yards after the catch. Running back Dexter Williams led the way in the screen game with three catches for 35 yards, with 46 yards after the catch.

• Play fakes opened things up a bit for Notre Dame’s offense. Book completed six of his eight passes for 98 yards with one bad throw and one drop following play fakes. USC pressured Book on only one of those eight dropbacks.

Takeaways

Eight unblocked pressures are too many for Notre Dame’s offense. We can’t put all the blame on the Irish offensive line, as communication with Book could contribute to those unblocked defenders. In some cases, those defenders need to be neutralized by quick throws by Book.

That was part of the adjustment the Irish made in the second half. Notre Dame countered by throwing early to running backs and receivers running open into the areas departed by blitzers. The game-sealing touchdown catch by Jones is the perfect example.

Part of what limited Notre Dame’s offense in the first half was the inability of any Irish wide receiver other than Finke to create separation. USC cornerback Iman Marshall stuck with Miles Boykin and Chase Claypool, and made it difficult for Book to complete passes. Book wasn’t as accurate as normal, but that was likely influenced by the tight coverage and not wanting to make a mistake.

Book’s big mistake did come in the fourth quarter when he threw an interception into the end zone. He forced a throw into traffic when an incompletion would have left the Irish in field goal range to extend the lead to 10 points. Book also got away with a throw back into the middle of the field in the first quarter. He needs to eliminate those bad decisions that could be costly in the College Football Playoff.