The Sooners gave Nebraska a defensive changeup last week. Before the 2019 season, Clemson defensive coordinator Brent Venables traveled to Ames, Iowa, to study Iowa State’s “3-3-3” defense. Cyclones defensive coordinator Jon Heacock devised the scheme as an antidote to the high-powered spread offenses dominating the Big 12, and programs around the country were picking up on ISU’s success. Venables is one of many defensive tacticians who have met with Heacock for a 3-3-3 crash course in recent years. Venables hasn’t adopted Heacock’s defense as a base alignment, but he has been known to deploy it when the situation calls…