Yes, Creek is overrated by some.
By all accounts, his ethic and workrate were appreciated in NBA training, but you have to remember WHY such things are appreciated in Fringe players and guys on 10-day contracts.
If they bring you in on a short-term contract because you're a gun shooter, there's a chance they actually want you on the bench to provide another scoring option if things go pear-shaped.
If they bring you in because you train hard, its because they want to put pressure on their bench players to lift their game.
He's done his best, and paid his dues in the G-League, from this point he would need some level of commitment to keep flogging that horse, and I assume he didn't get it.
To turn down what would be a very nice contract at SEM, and the chance to star in front of his "home" crowd, would be a big ask. (And then how long do you keep it up for? If he plays another year in the G-League and gets another couple of 10-day deals, does that mean he stays again??)
As for not being selected for the Boomers, as a backup player I think his lack of versatility hurts him. He is simply too small to backup the 4, and his 3-point shooting isn't good enough to play on a wing. He can basically only play the 3, and there's no doubt that Ingles and Cooks are ahead of him. To get a depth position, he would need to be more flexible, and/or offer a unique role-playing aspect. He doesn't.
He's just a bloody good SF.
It's like that bloke who was the 3rd best 1,500m swimmer in the world, and couldn't make our team because we also had 1 & 2.
He was the 3rd best SF in a team with only room for 2.