by PhilH » Sun Jan 19, 2014 4:18 pm
Re NFL -
For starters a lot of the 45 man squad get to play on game day.
Whilst there are only 11 on the field its a separate starting 11 for offences, 11 for defence and a few for special teams (kicker, long snapper, punter).
Then within each unit players come on and off for specific game situations.
ie 5 wide receivers probably rotate around, defences can be more lineman focused on short goal line stands or more defensive backs if a long yardage play.
Only a few won't normally play, the 2 back up quarterbacks (teams usually have 3 on their list) and possibly the lowest ranked player on the "depth chart" for each position. Injuries (of which there are many) can change that in an instant.
Those lesser used players PLUS those on the "practice squad" (not on the official list but assist at trainings) get used a lot at full contact practices during the week mainly as the "opponents" for the starters to practice against.
In essence NFL had a developmental league called NFL Europe which folded a few years back, a very select few come from minor Pro leagues, Arena Football or Canadian Football.
The main development pool is college players (There are approx 130 major colleges and hundreds more at a minor level).
With only 32 NFL teams, only a small pct of college players get drafted, leaving a huge pool of undrafted players waiting for a call.
Those drafted and many "free agents" fight for the few spots at training camp