I know what CrazyRazor is saying, because I am also having some defensive problems with my Gators team this year (CUST-10). There hasn't been too much turnover on the D, but something just doesn't seem the same this season. Last year's squad was 12th in the league in yards from scrimmage (defense). This year, they are 26th in that category. Maybe it's gameplanning, maybe it's the lack of quickness in the secondary...which wasn't there last year either, but results were way different.
I know Crazy's Redbone team is having the same problem.
So, if there are no changes in the game engine used yet, which it looks like there isn't, I guess I will have to go back to the drawing board for the remainder of the season...and have a good defensive draft next year!