Now this is mildly depressing.
11 flags for ex-Dees since 91. The 1991 premiership won by Hawthorn was the last time a premiership team consisted solely of players who had not originally played for another club. Since then 118 flags have won been won by players who had left their original club. Melbourne lead this ladder with 11 flags won by 7 different individuals. They also hold the longest stretch of premiership years having ex players win the flag from 2001 to 2006 in Martin Pike Brisbane 2001-2003, Matthew Bishop Port Adelaide 2004, Darren Jolly Sydney 2005 and Steven Armstrong West Coast 2006. Pike previously won a flag with North Melbourne in 99 whilst Jolly won another flag for Collingwood in 2010. The others are Earl Spalding (Carlton 95), Clay Sampson (Adelaide 97) and James Frawley (Hawthorn 15).
Collingwood, West Coast, Adelaide have also had four year stretches along with Sydney who are currently on a four year run with Shane Biggs (Bulldogs 2016), Toby Nankervis (Richmond 17&19) and Lewis Jetta (WCE 18).