It appears according to the rosters that the 1994, 1995, 1996, 1997, 1998 and 1999 defenses of Nolan's were 4-3. They ranked #8, #16, #10, #8, #28 and #24. His 3-4 defenses over the years ranked #1, #13, #19, #6, #6, #30, #32, #20, #23 and #12.
His defenses averaged #15.6 in the 4-3 and #16.2 in the 3-4.
If you insist on tossing out some of those 49ers years because of a bad stretch or bad players or whatever, I'd insist on tossing out some of those Washington years for the same reason. Then you're left with his 4-3's ranking an average of #10.5 and his 3-4's ranking an average of 9.5. Not really a whole lot of difference there, is there?