UCLA Defensive Gameplan

Up until the UCLA game, our defense had never given up more than 5 ypc against the rush, and had only given up more than 4 ypc twice. We'd only given up 150+ yards one time (to Colorado), and had held everyone else under 120. In the UCLA game we gave up 237 yards at 5.04 ypc. Why the sudden change? It's tempting to say that they're just better than the teams we'd played up to that point, but on the season they aren't that far ahead of UA. As always, it's a lot more complicated than the size, strength, and speed of your opponent.