Crew proficiency doesn't grant bonuses but give maluses on ships with insufficient proficiency. -10% Max CR per every point of missing proficiency.
Crew proficiency starts at 0 and end at 5.
Proficiency requirement factors are as follows
-1: Civilian-grade Hull (nullified by MS)
±0: Frigate, Low Tech
+1: Destroyer, Mid-line
+2: Cruiser, High Tech
+3: Capital Ship
Automated ships have no Proficiency requirement.
T4L, Cybernetic Augmentation, reduces Proficiency requirement of all ships by 1.
To compensate for the proficiency requirement factors, low tech ships now have lowest PPT while High Tech ships now have highest PPT.
Crew proficiency gain/loss works like Marine experience.