If you go back and look, though, the Patriots don't keep their own guys. By the end of the season, almost all of the practice squad will be filled with other team's guys.
Last year, we kept Lucien, and that was all. The rest of the practice squad guys came from elsewhere. The year before, at the end of the season, it was all other team's guys.
I think folks forget that the purpose of the Practice Squad is NOT solely (or even primarily) to be a developmental stash/farm team, although it sometimes functions as a deep backup reserve to cover for injuries.
Occasionally, the Pats have stashed a player on the PS for a week or two at the start of the season, and then called him up to become a semi-permanent fixture on the 53-man. And, toward the end of the season, the Pats will occasionally sign a new guy who they might be interested in taking a closer look at for the following season.
But, mainly, the PS is the backbone of the Scout Team. PS players and special-teamers/roster-end guys from the 53-man combine to form an offense that mimics the offense of the Pats upcoming opponent for the primary defensive players to practice against, and a defense that mimics the defense of the upcoming opponent for Brady and the #1s on offense to practice against.
Brady and the #1s on offense can't be spending precious practice reps during the week mimicking the opponent's offense for the benefit of the starting defense. Brady and crew need every rep to install and practice their own game plan. Same for the defensive #1s.
So, the guys who end up on the PS are selected because they can fill a role on the Scout team. Sometimes they're the Pats own cuts; frequently they're not. In any case, PS players generally spend very few of their practice reps rehearsing the Pats' own system, schemes and playbook for the sake of furthering their personal quest to graduate to the 53-man. Instead, they're always working some other team's stuff.
During the regular season, the Pats will often drop a guy who's been on the PS for several weeks and sign a different guy, often at a completely different position. Then, a week later, the new guy is cut and the previous player re-signed. It's often assumed that the short-term pickup simply failed his "tryout". In fact, the guy was typically hired as a "temp" to portray the role of a specific player on the upcoming opponent's team in practice.
Although the PS is limited to 10 players, by the end of the regular season, perhaps as many as 20 different guys will have rotated through it. Out of the maybe 200 players who have, at one time or another, been on the Pats' PS over the past 16 seasons, really relatively few have ever "graduated" to full-time 53-man roster status in New England.
