DBZ has been getting lower ratings for a while, although we haven't had Goku in a while so that may be the reason, show consistently outperformed every other show for a while, and now its starting to fall in line wifh the other shows
I dont think it's likely, but Jojo has a huge amount of hype for it
Here are the last 8 weeks, only looking at DBZ Kai and KLK
June 20th
12:00 AM Dragon Ball Z Kai 1,157,000
12:30 AM Kill la Kill 1,180,000
June13th
12:00 AM Dragon Ball Z Kai 1,383,000
12:30 AM Kill la Kill 1,138,000
June 6th
12:00 AM Dragon Ball Z Kai 1,261,000
12:30 AM Kill la Kill 1,201,000
May 30th
12:00 AM Dragon Ball Z Kai 1,385,000
12:30 AM Kill la Kill 1,077,000
May 23rd (Memorial day weekend KLK marathon)
12:00 AM Dragon Ball Z Kai 1,330,000
12:30 AM Kill la Kill 978,000
May 16th
12:00 AM Dragon Ball Z Kai 1,163,000
12:30 AM Kill la Kill 1,015,000
May 9th
12:00 AM Dragon Ball Z Kai 1,403,000
12:30 AM Kill la Kill 1,145,000
May 2nd
12:00 AM Dragon Ball Z Kai 1,266,000
12:30 AM Kill la Kill 1,058,000
And if we go one weekend back DBZ Kai was at 1,636,000 but I'll stick with 8 just for my average
Kai over the past 8 weeks has averaged 1,293,500 viewers which is around what Bleach averaged when it lead the block at midnight for years. Kai has not been getting lower ratings for awhile it's been doing very well. Yes it had a few 1.6+ million weeks, but those were abnormal and dominate the top 5 highest ratings for a single show since new Toonami began.
By comparison Kill La Kill the second highest rated show (only looking at it's 12:30 showings ignore the marathon) has averaged 1,099,000 over the past 8 weeks. Not once in that run did it ever beat Kai's average ratings. Hell for giggles I'll take out the 12:30 rerun night from the average and put in the last week of April the only week KLK would have beaten Kai's average (1,356,000) and that only boosts the average to 1,146,250 which is still lower then any one week of Kai. Remind you the night KLK did 1,356,000 Kai did 1,636,000.
Any way you look at it your comment that Kai is slipping makes no sense. The stretch from late February to April where Kai did 1.4~1.6 million a night was the show doing exceptionally above expectations. That stretch was the highest stretch of any show in the history of new toonami outdoing and stretch of Bleach, to expect ratings that high consistently is foolish. What we've seen in the past 2 months is far more normal ratings for Kai. If we start seeing Kai do below 1 million for 4-6 weeks straight then we can talk about Kai slipping and at that point Toonami is DOOMED.