Players on practice squads get very little public attention during the season, but teams sometimes rely on them heavily for depth during the week.
NFC West teams are carrying the maximum eight-man allotments heading into Week 4. My updated 26-column rosters, available for download here, feature players on practice squads and active rosters, plus former players and those on reserve lists.
The charts below break down positional counts for 53-man rosters and practice squads.
The St. Louis Rams have only seven offensive linemen on their 53-man roster, but with three more on the practice squad, they're able to function during the week.
The Seattle Seahawks have only two tight ends on their active roster, but they have three available to them for practice, plus Cameron Morrah, who remains on the physically unable to perform list, and John Carlson, who is on injured reserve. Former tight end Jamison Konz, now one of two defensive linemen on the practice squad, helps numbers at his current position.
A few notes on practice squad players, straight from the collective bargaining agreement:
Practice squads are limited to eight players at a time.
Players on practice squads are eligible to sign with any team's 53-man roster, but they cannot sign with their current team's next opponent later than 4 p.m. ET on the sixth day preceding the game (10th day during a bye week).
Minimum salaries for players on practice squads are $5,700 per week in 2011 and 2012, escalating throughout the 10-year labor agreement. Salaries peak at $8,400 in 2020.
Players are eligible for practice squads if they have zero accrued seasons, and when they spent fewer than nine regular-season games on an active roster in their lone accrued season.
Players can spend two seasons on practice squads, with a season defined as three or more regular-season or postseason games. They can spend a third season on a practice squad, defined as one or more games, if their team keeps 53 players on its roster at all times.
Any player signed from a practice squad to an active roster is guaranteed three weeks' salary at the 53-man level, even if he's released before spending that long on a roster. The player will count on the team's 53-man roster for three games, with a bye week counting as a game, unless the season ends first.
There are a few more specific rules, but these are the basics.
2011 NFC West Roster Counts: Week 4
Bigger numbers for a position on a practice squad usually correspond with smaller numbers on the 53-man roster.