I'm tired of the fact free discussions about pass rush/secondary causality. Does a weak pass rush cause a bad secondary or does a weak secondary cause a bad pass rush.
So let's put together some facts. Let's look at:
Teams that added/lost an elite CB
-change in sacks for the team that added the CB
-change in sacks for the team that lost the CB
Obviously this will be imperfect but at least its a start at looking at the relevant data.
I'll do Deion Sanders.
1993 Atlanta Falcons (w/ Deion Sanders): 26 sacks
1994 Atlanta Falcons (w/o Deion Sanders): 32 sacks
1993 SF 49ers (w/o Deion Sanders): 44 sacks
1994 SF 49ers (w/ Deion Sanders): 38 sacks
1994 Dallas Cowboys (w/o Deion Sanders): 47 sacks
1995 Dallas Cowboys (w/ Deion Sanders): 35 sacks
Please think of other examples (e.g. Charles Woodson, Champ Bailey, etc) and post your results in the comments.
the pro football reference 'teams' page is invaluable for this exercise.