Probably an unpopular take here but there seems to be this notion that free throws should be free.
That if you are a bad free throw shooter, it just means you need to practice them more to get better.
Maybe that's the case for some but I just think it's a skill just like anything else. Each player is going to have things they are good at and things they aren't good at. It doesn't mean you can't improve through practice but I feel like with players there's certain ceilings on these things.
Like if Butler is a career 68% free throw shooter, he's not going to magically change to become an 80% one. Through practice maybe he could up it a bit, but to me it will always be marginally.
Unless something changes drastically with a player (like a coach points out a flaw in their shot or something), you don't typically see wide differences from year to year. The best estimate for Butler going forward is what he's already shown to do.
That would be the case if Butler shot his free throws like Bill Cartwright, but since his shooting form and release is very good, it comes down to mindset and concentration, maybe a little bit of muscle memory.
This is something you do have to practice to get your range down.
These guys have all proven they can hit them, but for some reason, they go through spells where they miss. This isn't about talent.
Heck, Amari Williams sucked at the beginning of the season, it's obvious he worked on it, he is much better now.