Griffin > Jabari.
Griffin > Enes.
Just based on that the Celtics are already better as a team.
He cannot switch on defense or defend the perimeter. However, he ranked very high in stats as an interior defender last season. As a back up center for 10-15 minutes until TL returns he should be fine.
Interestingly, Griffin, White, and Smart all are very good at taking charges.
He did start 20 games last season (for a playoff team, I guess.)
An all right pick setter, and occasional roller.
I have no trouble with this signing and whoever is bumped from the team is not really NBA material anyway.