There are two ways to do this: You can go with how the move was seen when it was made or how the move ultimately turned out. I will go with the former.
1. Thabeet...this single move likely cost us a championship especially since we had an assistant GM that loved Curry. However, even if we take Tyreke Evans, we likely have better roster balance. Never trade for Ronnie Brewer. (for some perspective, the 1st rounder we used on Brewer could have netted us Jimmy Butler) Could easily transition Mayo to combo guard off the bench.
2. Passing on Draymond Green even though he had a great Memphis workout.
3. Ignoring the head coach and passing on Rodney Hood
4. Not giving Rudy Gay the contract he wanted and then giving him more than you can afford less than a year later.
5. Waiving Hasaan Whiteside then not having a backup for Marc that eventually cost us having Ennis on a much more favorable contract.