If you are predicted at #28, and I'm guessing you are looking at somewhere like NBAdraft.net, then you probably shouldn't go out because it's too much of a risk to slip into the second round, where you're not guaranteed a contract.
It's a business decision for Tobias.
If he gets a lottery-level evaluation, he's probably gone. If he gets a 2nd-round evalutaion, but he hates the new coach, he probably leaves. If he gets a 2nd-round evaluation and he thinks the new coach can help his game, he stays.
He'd be foolish to make his decision at this point...it's business, not emotional.