Generally, when analyzing team needs, the thinking is, "Team A has a hole at position X, so Team A should draft the best X they can." This is logical, but it can be overly simplistic.
What must be taken into account is what we'll call a team's "pillar need." A pillar need is a need that a team has perpetually because of specific but important characteristics of its scheme and philosophy. A lot of times, there isn't a dire necessity for new talent at a "pillar need" spot, but with depth there being extra important, teams will restock the position anyway -- especially with mid- and later-round picks. Understanding a team's pillar needs leads to a clearer understanding of the team as a whole.
Pillar need: safety
You look at New York's defense right now and alarms sound when your eye spots the holes at outside linebacker. Aside from journeyman backup Antwan Barnes, not a single Jet has meaningful NFL experience at this position. No coach, including Rex Ryan, can run a 3-4 scheme with lousy outside linebackers.
Perhaps more troublesome, though, is New York's situation at safety. Right now, penciled in to start are last year's sixth-round pick, Josh Bush, and seventh-rounder Antonio Allen. Needless to say, the depth behind these unknowns is iffy.