Neilon has had an excellent last couple of years in particular for the Trojans, as he not only allowed a single sack last season in 534 snaps (most without allowing a sack in Power 5 per PFF), but continued his elite performance this year too.
The sixth-year player is even the name behind the "Neilon Nudge" at Oregon State. It's no surprise that SC fell apart as soon as Neilon went down in the Pac-12 Championship Game, after they had finally crawled back into the game down 10 and were on Utah's side of the field, ready to score.
When asked if Riley knows of any player on the roster who won't be available to play in the Cotton Bowl for opt-out reasons or injury reasons, Riley said that besides Neilon, "our expectation is everybody else would be available." More on that below from Ryan Young of Rivals:
With Brett Neilon out, USC Football will likely move Justin Dedich from Right Guard to Center.
And Dedich will play well at Center for USC Football in Brett Neilon's place. Remember, Dedich has not only played center for USC at times throughout his Trojan career, but he also was a center in high school.
He was a great one at that, too, as he was the No. 2 overall center in the country coming out of the 2018 recruiting class (all recruiting rankings and ratings in article are as of 247Sports). The four-star prospect was the No. 14 player in all of California.
The issue is also not that SC is likely going to have to move Jonah Monheim from Right Tackle to Right Guard, either. Monheim was recruited as a guard out of high school. He was a four-star prospect that way, and the No. 16 guard in the nation. The issue is that SC is then going to have to fill the empty Right Tackle spot with Mason Murphy.
Murphy has had some good moments for USC this year, but he's also had some bad ones, such as the Pac-12 Championship Game. It's tough because the Trojans may very well get their No. 1 Offensive Lineman in Andrew Vorhees back for the bowl game, but then will be missing their No. 2 Offensive Lineman in Neilon for the bowl game.
It's going to be a crucial test and learning experience for the offensive line and its depth on January 2nd, against a Tulane defensive front that was tied for just 80th in the nation with only 24 sacks this year.