The Celtics don't have a big shot blocker or even a "true" center in the rotation. This was supposed to be a problem but, so far, they are the #2 defensive team in the league.
Also this season, the bottom 6 teams in the league in DRtg are the Bucks (also no real rim protector), Pelicans (Anthony Davis, Omer Asik), Nets (Brooke Lopez), Lakers (Roy Hibbert), Rockets (Dwight Howard), and Clippers (Deandre Jordan). Having big in the middle guarentees you nothing.
The Celtics are joined in the top 5 by the Spurs (Duncan, Aldridge), Heat (Whiteside), Pacers (center-by-comittee that includes Ian Mahinmi), and the Warriors, who play Bogut and Ezeli big minutes but whose best defensive lineups have Green at center.
So what does this all mean? Can the Celtics maintain a top-tier defense with this group for the season? Is bringing in a very tall person still a priority?