Hard to give much input, because we didn't see any more 4-2 than we did 4-3 or 3-4, or even 3-3. We were very diversified in how we lined up on defense. Unfortunately, we never found anything that worked.
I'm not typically a fan of nickel base defenses. If you are going to run one, you better be tough as nails with your front 6, if not you get run over. Additionally, you better have three safeties who can play well, since you have 3 of them on the field. We were one Todd Raynes away from essentially having no serviceable safeties.