There’s no way of getting around the fact that NFL rosters are cyclical in nature. Every year at a minimum, hundreds upon hundreds of new players enter the labor market for just 32 NFL teams, each of whom field 63 players per season, plus those on injured reserve and other non-active lists.
With hundreds of players drafted every year and just as many if not more coming in as undrafted free agents, it’s inevitable that some of the 2000-plus players with NFL contracts from the season before are going to lose their spots. Some teams see far more turnover than others on a regular basis.