Football news in general is unusually slow this week, so I've been on the hunt for something of interest. Lo and behold, I stumbled across a neat section of Football Outsiders that details and explains offensive packages. On days like today when the biggest piece of news is the fallout from the Walt Harris injury, we do some learning. Just like with the Advanced NFL Stats pieces, you'll want to go see how deep the rabbit hole goes. Note: this piece was written in 2007.
Since there are four separate variations of the screen detailed, I won't go grab chunks of text to work with. You'll want to read each in detail. What stands out in each play is the precision timing and sleight of hand required to pull each screen.
The Deangelo Williams screen works because the Panthers break in a standard formation, creating a mismatch by splitting Williams out wide.The Cowboys screen creates confusion by bunching there wideouts to one side, but is foiled by timing and a poor Romo throw. The Walker play requires precision spacing and timing of blocks so that Walker has space to pick his way through the gap. Mark Campbell's fake screen needs two separate ball fakes by Drew Brees in combination with the right sell on the pass block by Campbell himself.
If you ever got the impression that it's not that difficult to pull off a play on a football field, hopefully you've corrected mental error.