NFL teams play only sixteen games in a season because there is a much greater risk of both collision and fatigue-related injuries than in Baseball, Basketball or even Ice Hockey. Basketball and baseball are not collision sports like gridiron or ice hockey, and ice causes much less fatigue for players than the hard grass or synthetic surfaces on which gridiron football is played.
The result is that, whereas the NBA, NHL and MLB can have several games per week, this is impossible in the NFL: players would be exhausted beyond their physical capacities.
The reason for the fifty man roster is for depth on the team if there are any injuries or tired players. Eleven people are on the field at once for each team. Some players are designated to play special teams. 22 starters, maybe about 5-10 designated special teamers, a kicker & a punter make up 34 of the players right there. In basketball for contrast, you're only fielding five players at a time with a bench of about 5 more.
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Click on the '2007 Patriots Roster' link below to see the players on the New England Patriots 2007 roster.
The two players that were on both the 1996 roster and 2008 roster are LB Ray Lewis and K Matt Stover.
The 2009 New York Yankees had 37 different players on their Major League roster.
Full roster is 40 players
There are 26 players on the Phillies roster.
There is no limit to the amount of players that can be on a college football roster during the regular season. However, during the off-season the NCAA regulates that a total of 105 players are allowed on the roster.
Click on the '1987 Steelers Roster' link below to see the roster of the 1987 Pittsburgh Steelers. All players listed that have a caret (^) next to their name were replacement players.
Each team can have 25 players on its active roster in the postseason. They can change the roster between rounds, for example replacing an injured player with another player on the 40 man roster.
There are two rosters in Baseball; the 25-man roster and the 40-man roster
A baseball roster is a roster that typically consists of active players for a baseball game such as for example in Major League Baseball all 30 teams have a 25-man roster starting from Opening Day of the regular season until and including games on August 31st however starting on September 1st all teams are allowed to call up any players that are not on their 25-man roster but are currently on their 40-man roster, teams will have 40-man rosters as their active roster until the end of the season.
You can look at the roster at orioles.mlb.com