Even if PASI 75 was 20% including all arms at 6 weeks with 70%-80% complete, it's possible no assumptions can be made in comparison to Otezla until all 12 week data is known. At that 70-80% 6 week point, probably only 55%-65% are done with their 12 week treatment.
Some may view 20% PASI 75 halfway thru as not good, without consideration of waiting for the complete 12 weeks of treatment to finish.