Screens are not bad plays to run, its not like every coach in the NFL and majority of coaches are all retarded and like to run it just so they have it in their system. If it is employed with the right personnel and run correctly they can be very effective. With the 320+ linemen we have the last few seasons running down the line and trying to get in place with thier blocks before a pass is thrown is why they havent worked. You need athletic lineman to execute screens and just to clear things up taking a slow 330 lb lineman and making him lose weight to 300 doesnt all of a sudden make him an athlete. You also have to have receivers with a big move set that dont have to be incredibly fast but must be agile and shifty. Also depending on the screen you have to have receivers that aren't afraid to make a hit and block.