This is very predictable.
Always, always, always be skeptical of the power conference school that runs out to a great start against a steaming pile of nothing in the non-conference. Teams like that are, far more often than not, complete frauds. Especially if they're traditionally 2nd-tier teams (like SC).
USCjr's OOC schedule is rated 289th by Pomeroy.
Other strong candidates for major regression-
Pitt (14-1, schedule 323th)
Baylor (12-3, schedule 318th)
Ole Miss (12-3, schedule 313th)
The ville (13-3, schedule 300th)
Arizona (13-3, schedule 287th)
IU (14-3, schedule 278th)
West Virginia (15-1, schedule 276th)
A team can only play what's on its schedule, so sometimes a weak OOC means little. But having success against a 2 month run of almost nothing but bad teams often doesn't indicate any ability to sustain that success against teams with equal talent.