USC's own scoring defense isn't exactly terrible. UConn has played against 9 opponents with scoring defenses ranked in the top 200, compared to USC having faced 16 opponents with top-200 scoring defenses. The Gamecocks have gone up against only 6 opponents who fell from 201-on in scoring defense rankings, compared to the Huskies facing 13 opponents with such poor defenses.
And while how well a team keeps it's opponents scores low can depend highly on the quality of opponents that team plays, UConn has played against 15 opponents with SOSs ranked in the top 100, 5 in the top 200, and 2 outside of the top 200. USC has played 17 opponents in the top 100, 3 in the top 200, and 2 outside of the top 200 as well.
So UConn plays against the lesser scoring defenses compared to USC, and against a slightly but definite lesser quality list of opponents than USC has played. Further when you add in that UConn has played it's starters more minutes per game in those games than what USC has played, and that UConn has the more experienced and older roster, the difference in scoring offenses makes more sense.
The best-ranked scoring defense UConn has faced this season prior to USC was St. John's who currently has the 32nd-ranked scoring D. Better than Stanford's (96th), Duke's (47th), and Notre Dame's (104th). St. Johns also has a fairly decent SOS at 83rd, meaning that they played that great defense against a solid lineup of opponents. They held UConn to their lowest point total of the season at 70 pts.
USC will bring a much better scoring D that it built against a much better quality of opponent to Storrs this Monday: The Gamecocks haven't faced a #1-ranked scoring D yet this season, but they have played against some pretty solid scoring Ds owned by teams that have gotten theirs against better competition that UConn has faced. So we'll see.....