While USC will always be formidable because of its card carrying status as a blue blood program, they are really hurting right now. The Bru McCoy transfer was a big deal in football circles here in Texas, and Hewett - being at North Shore with many other high level recruits - would certainly be plugged into the story. You just don't see a guy like McCoy - lifelong USC fan, 5 star recruit at Mater Dei - seek to transfer after 2 weeks at school (and face the possibility of sitting out a season), just because his OC left to take another job. Supposedly the relationship/communication between coaches and players is terrible and the culture is really bad. There's a very strong chance Helton gets canned next year, along with Swan the AD, and a new guy comes in with a mandate to clean house and change the direction of the program. Fit is everything in a college football program, and a guy like Hewett could easily find himself blowing 2-3 years of his eligibility swept up in the chaos and its aftermath there.
I'll never be totally surprised seeing any recruit pick USC, but this USC situation is very, very different from a typical USC situation.