Football Analytics is a website dedicated to the analysis of the National Football League using mathematical and statistical methods.
As you can see, the picture on the bottom left shows when split are 3 ft wide, the right one shows that the splits are 1 ft wide.
So lets say no one is blocking in offense line. In the 3 ft splits the defense linemen have to line up about 27 ft wide, and the 1 ft splits they need to line up about 16 ft wide.
This really make difference
How it make difference?
You can see in the diagrams. Let's say when offensive linemen are blocking. The Defense line will come try to get to the quarterback with a elliptical shape. Which is mean the outside guy will have most chance to sack the quarterback. When we have a 3 ft splits line. They have to travel more distance to get to quarterback. But in 1 ft splits, They will travel less distance. So that's how splits work in football.