Teams are required to list on the injury report any player who might not play in the next game because of health reasons. They also are to list the area of the injury--such as "shoulder" or "leg"--but they need not specify the nature or severity of the injury. In practice, however, teams are incredibly circumspect. As noted by USA Today in a 2007 analysis, teams coached by Bill Parcells rarely listed a player unless he was totally unable to play. At the other extreme, the New England Patriots put quarterback Tom Brady on the list every week for more than two years--and he started every one of those game. Former Pittsburgh Steelers coach Bill Cowher admitted he would sometimes misidentify the location of an injury--putting down "knee" instead of "ankle," for example--to prevent opposing teams from targeting that player's injury if he played.
The report must classify every player on the list as "out," "doubtful," "questionable" or "probable." According to league guidelines, when a player is listed as "probable," he's more likely to play than not play. "Questionable" players are those with a 50-50 chance of playing. If there's a 75 percent chance a player will not play, he is "doubtful." And a player who's "out" will definitely not play.
Each team must submit its injury list to league headquarters the Friday before each game and update the list on the weekend as needed.
The league office can fine teams for filing inaccurate injury reports. For example, the NFL fined the New York Jets, their general manager and their former coach $125,000 for hiding that quarterback Brett Favre played with a torn tendon late in the 2008 season--an injury that came to light only after Favre told reporters about it. Still, injury-report fines are rare. USA Today's analysis turned up just 13 in a 10-year period.