The Celtics lost all their tie breakers.
Amazing how they never seem to get luck in the draft
The Celtics actually won with the Memphis pick. It could have been from 7-9 and they'd get it at 9 (protected 1-8). However, Memphis is pretty much a wreck now so there's a good chance it will have a higher pick in coming years. The pick is 1-6 protected next year and unprotected the year after. The risk is that when they do the lottery one of the teams from 9-14 will jump over Memphis and they'll will drop back to 9. There's a 39% likelihood that will happen and it's pretty much the worst case scenario.
Edit: If they are truly incredibly unlucky, there's a 1/2 of one percent chance that the Sacramento pick jumps up to 1 in the lottery. In that case, the Celtics would get the #24 pick and he 76ers will have the top pick.