Further support for them falling to the 2 seed - would line them up for (most likely) Indy (3-1), Toronto (3-0), and then most likely Boston (3-1), which they're 9-2 against collectively.
If they retain the one seed, then they'll most likely play either Miami (1-2) or Chicago (0-4), Washington (2-1), and then Boston (3-1), which they're 6-8 against.
So it actually probably makes the most sense for them to rest their guys and take the second seed rather than play their guys and fight for the first seed.
EDIT: and that's if Atlanta doesn't beat Washington in the first round. If they do, then that would set up the number one seeded Cavs with the Hawks (1-3), which they do not want this year. So, yeah, the two seed actually gives them a much easier road through the East than the one seed.