EVERY recent coach has hired bad assistant coaches including LaVell and has had to replace them. Don't get caught up in any recency bias.
Detmer and his staff were horrible but were they Kalani's call? Hard to say. He fixed the problem though.
My biggest complaint with Kalani is that he was too slow to replace Tuiaki. I get that Tuiaki was his friend/de facto family member so Kalani kept trying to elevate Tuiaki's abilities through various means and unfortunately none worked. It's also too bad that Tuiaki couldn't or wouldn't learn and grow.