33 is the absolute ceiling for ranking those defenses (not to get too semantic but 33 is not top 25).
But when you add in the other respected rankings like F+, PPD, etc., it looks closer to 40-50 on defense. And 2016 was our best defense. Meaning we aren't in any form trending upwards.
Maybe we have worse players now than in 2016 (that doesn't bode well either though).