I think it is obvious the Pats defensive coaches are not learning anything.
Pete Carroll first year in Seattle (2010) they were 25th in the NFL in terms of points allowed, last year, they were 7th and this year the are currently 2nd. That is improving a defense. Their starting defensive back are one first round pick (Thomas), two fifth round picks (Sherman & Chancellor) and guy who went undrafted and spent five years in the CFL before Carroll brought him back to the US (Browner).
Meantime, over the past four seasons, the Pats have gone from the 5th defense (in terms of points per game), to 8th, to 15 last year, and currently sit at 17th. All despite, a myriad of draft choices on DBs that have come and gone in that time.
However you spin, that is not good coaching.