If you are in need of some fresh ideas for [tag]line backer football drills[/tag], try this one.   An added plus is that it is fun and the players love it.

Set up two rows of pop up bags (any soft obstacle will do) about 5 yards apart with a bag every 10 yards and staggered.
Get two LBs to run down the parallel rows at the same time passing a [tag]football[/tag] back and forth.
They must make contact in some way with each pop up. This forces them to use their peripheral vision or have their head on a swivel to keep track of the pop ups while focusing on the ball.

It is very helpful in avoiding crack back blocks and such while in pursuit. I have them start at half speed and work up to whatever speed that they can do it at. You can also make it competitive; your players will love it.