Appears that Udeze was hired to USC by Sark, then Helton promoted him to DL coach. This is what Helton said about Udeze when he promoted him.
"There are times in your career when you meet someone and just know that they are going to be a superstar in the profession," Helton said in a statement released by the school. "Kenechi is that person. I was blown away by his attention to detail with technique and fundamentals in our recent bowl game preparation and in the interview process. His knowledge of the game is something that is going to be critical to the development of our young defensive line. Kenechi is a Trojan to the core and his passion for USC is felt by all."
Unless Helton was blowing smoke up the local sports scribes' read ends, he thought pretty highly of the dude in 2016.
It's very possible that Udeze was collateral damage in Helton's effort to stay on as HC.
I thought the conventional wisdom was that NU needed to up the talent level at DL. If the guy is an ace recruiter, he checks that box.