The deal that works on the ESPN trade machine is Bradley + Crowder for George. Hollinger minus 6 for Pacers. It puts the Celtics very close to the cap money needed to sign Hayward, too. There is still some uncertainty about the max salary in view of the adjusted cap to $99M.
A straight deal makes the most sense without 3rd parties getting involved. Most likely, they were close to a deal draft night, but maybe Ainge decided to wait until after they renounce Zeller 7/2 and sign Hayward.
The straight deal, no draft picks, looks good for both teams. Bradley is cheap next year. Crowder is cheap for two years. The Pacers can extend Bradley, and if they don't, the Celtics could re-sign him if George does not stay in Boston. If George doesn't stay, they have enough to extend IT.
The core team would be IT, Horford, Hayward, George, Tatum, Brown, Smart, Rozier. Dropped players: Zeller, KO, AJ, Jerebko, D Jackson, Mickey.
They'll have to fill out the roster with cheap players, Zizic, etc. This is how the elite teams are doing it.
You need a core of 8-9 good players to win a championship. Red always said 8. They would be close.