Stetson Bennett was a walk-on who led his team to the national title game
Brock Purdy was a Mr Irrelevant who became an MVP candidate
Nick Saban was only a fairly solid coach at Michigan St before becoming the GOAT at LSU and Alabama
All of these things CAN happen. But most walk-ons don't carry their team to national titles. Most late round draft picks don't become MVP candidates; most don't even stick around. And most mediocre coaches don't become elite.
The existence of exceptions is a good thing, but that exception still should not become the expectation
It's possible Kalani is an all-time elite HC just waiting to break out. It's also possible he's really a terrible head coach just buoyed by circumstance. But (by far) the most likely case is that he's who he appears to be - a perfectly OK, mostly adequate head coach, not great but also not bad