Why did Spagnuolo stink as Saints' DC? (merged)

We fielded the #4 defense (both yards and scoring) the very next year

Let's see if we can figure out personnel changes
Also note we switched from the 4-3 to the 3-4
Im listing only starters, although Galette and Hicks were on the roster in 2012


Code
     2012                      2013
DT   Buntley/Ellis             Buntley(NT)
DE   Jordan/Smith              Jordan/Hicks
ILB  Lofton (MLB)              Lofton/Hawthorne
OLB  Vilma/Shanley/Hawthorne   Galette/Harlson
CB   Robinson/Greer            Lewis/Greer,White
S    Harper/Jenkins           Vaccaro/Jenkins

I don't think the 2012 roster was devoid of talent. The problem was there had some very obvious "weak links" which could be exploited, combined with a poor scheme and guys not being in the right spots. If I remember right Sedrick Ellis was a major one. Roman Harper had also lost a step, and I remember Vaccaro making an immediate impact. You can add Keenan Lewis replacing Patrick Robinson to that list.
That just reminded me that Vaccaro got injured and may have returned at the end of that season. I think a wrist injury or something. I could be wrong.