No. 2 Clay Helton (2015-21)
Often, coaching hires are reactive moves. Those making the decision usually go for a candidate as opposite from the previous coach as possible. That's not always the way to make a quality decision, though. Such was the case with Clay Helton.
When he was tabbed the interim head coach to replace Sarkisian in the middle of the 2015 season, he was about as different from Sarkisian (or Kiffin) as possible. He was safe. He was reliable. He wasn't going to bring any more embarrassment to the program, at least off the field. That was appealing to a program that had seen its share of controversies since the end of the Pete Carroll era.
What's more, he won five of his seven games as interim head coach before he was appointed the permanent man in charge. However, those in power should have known that his success was fool's gold.
After all, he simply didn't have the qualifications to run a program as high-profile as USC. The problem, though, was that Helton was so liked as a human that those in power overlooked the shortcomings on his resume. He had never been a permanent head coach at the collegiate level so to expect him to be able to restore USC to its place among the nation's elite was laughable.
The problem, though, was that he had early success. In his first season, he led USC to a Rose Bowl win. Then, in 2017, the Trojans won the PAC-12 title.
However, he couldn't sustain the success that had been built largely on the backs of Sarkisian and Kiffin's recruiting efforts. In 2018, despite the PAC-12's collective struggles, he managed to go only 5-7. He would rebound with a decent 8-5 campaign the next year but a loss in the Holiday Bowl isn't up to USC's standards.
In 2020, he guided his program to a 5-1 record in the odd COVID-19 abbreviated season. What's more, the pandemic might have bought him some time as the chaos of the world certainly distracted people from his struggles as head coach. However, in 2021, he was fired just two games into the season after a disastrous 42-28 loss to Stanford.
Helton is by all accounts a good man and his maturity and responsibility were needed after the Kiffin and Sarkisian debacles. However, USC needed more than just a good man. It needed an elite coach and that isn't what Helton was.