I can't say, but apparently this was an animators attempt to solo key animate an episode. Considering the amount he did on 915, this should probably be another impressive effort, if not exactly to the standard of 915. Expect it to be quite animated for the action scenes(you could probably tell that just based on the preview).
well most likely it is Snack there are reasons for that:
first of all Cracker was surprised that Luffy was able to destroy his armor , and Smoothie should be stronger and without a doubt Katakuri is not the one, otherwise he could have mentioned that in his fight with Luffy , he is the strongest sweet commander .
secondly Snack as he was introduced in chapter 894 he was angry and talking to himself mentioning the worst generation , i doubt it is only because of Urouge , i think BM degraded him because of his apparent weakness against the supernova