I'd say Heacock's 4-3 schemes were some of the more complex in the college game that I witnessed. We utilized plenty of confusion and multiple sets (4-3, 5-2/4-3 hybrid, 3-3-5 nickle) in variation of the 4-3 to create pressure and it worked very well. Even though the 3-4 has the reputation of being the more subtle and technical defense, I think the 4-3 can be every bit as complex and effective if utilized properly, especially with fast and powerful ends who have the ability to drop into coverage or rush the passer.