It does not excuse the level of epic awfulness that they have achieved, but the New York Jets have faced a very difficult schedule of opposing defenses through three games. The Panthers, Patriots, and Broncos rank first, eighth, and fifth, respectively, in defensive DVOA (defense-adjusted value over average).
Defensive DVOA accounts for strength of schedule, so those teams do not get an extra boost for playing the Jets’ weak offense. Those three defenses have just been legitimately great thus far.
Based on DVOA, the Jets have faced the most difficult schedule of opposing defenses in the NFL through three weeks.