Actually, by year's end, none of them were even full-time starters at all, let alone "key".
Dana Stubblefield is not a member of the Patriots.
Harrison is still a top safety, and hardly past his prime. Poole is coming off an injury, but had great numbers in '03. To top it off, they added Duane Starks, who's a very good corner when healthy.
Seems like your knowledge of the Pats' players is sub-par at best. Might want to study up on them before you spout off again.