It not shocking to me even though the staff expected everyone back. Walter Berry had lead everyone to believe he was coming back only to change his mind at the deadline.
It comes down to it doesn't matter what we think or whether or not he got good advice. It comes down to what the player thinks and what he wants to do.
Casey Jacobsen played for Stanford a few years back and decided to apply for the draft after his junior year. The reason was that it didn't matter if he went after his junior year or waited another year, he was projected to be drafted upper mid to late first round either way, so why wait if he wanted a shot? The first contract is slotted/capped. It is the second one that player's who show promise who make a nice salary jump, so it is one more year of potential earning.
There are no slam dunks in the draft as everyone has flaws in their game. Of course you have some with higher ceilings, are more advanced, more talented and less flawed. Jakarta at times looked like he regressed while at other times his 12 - 15 footers were deadly. No doubt I believe another year would have helped and yes it is a big lost especially with no one readily apparent to replace him. That makes four open scholarships.
You don't think Lavin had a clue? If not, he should have. Not that it would have changed anything.