Guys like BBD & Bass have actually been pretty efficient at center in the past. If you have the strength to defend the post, players 6'7" or so and up can be perfectly useful as centers for 10-20 minutes per night. There are only so many centers that will be able to take advantage and shoot over them if they don't get great post position. What's bad news is when you don't have any other options. In that case you'll periodically get killed down low.
Assuming Pierce and KG play 65 MPG, you've got 5 guys (Green, Sullinger, Melo, Steimsma, JJJ) competing for 79 minutes of player time at the 3/4/5 spots. Not a bad problem to have, especially since Sullinger & Green are starters on most teams. And that's not counting Pietrus at the 3 or whoever else we sign.
People have droned on about the new athletic NBA... what I like is flexibility in the playoffs. How does a team like Miami defend the post against a lineup with Green + Sullinger + Garnett? Go with Pierce / Green / Garnett and we have good scoring punch but can matchup better with Lebron at PF.
In conclusion, glass half full.