Early on Wednesday, Chicago Bears linebacker Lance Briggs posted a tweet that said he was having a “shaking my head moment” because his teammate Jon Bostic was fined $21,000 for a hit against the Chargers in last week’s preseason game.
Shaking my head moment. Nfl fines jon bostic 21k for his clean hit against the chargers.
— Lance Briggs (@LanceBriggs) August 21, 2013 
Briggs compared Bostic’s hit to the one that knocked Dolphins tight end Dustin Keller out for the season and, as many others have done with similar hits, wondered why the former is illegal while the latter is legal. Ian Rapoport of the NFL Network confirmed Briggs’ report and adds that Bostic was fined for lowering his head while hitting a defenseless receiver.
Source: Josh Alper, NBC Sports Pro Football Talk