On those plays, the 'open' WRs weren't primary reads. Terrence said after the game that the coaches had been harping all week on Weeden making his first two reads and then checking down to Dunbar where they liked the matchup underneath, and that's what he did. So it was by design.
I didn't see what xwalker did with WRs running free downfield very much unless it was when ATL was playing soft coverage on 3rd and 10 or more, in which case they were all guarding the sticks and watching the QB for the throw where they had a significant numbers advantage. I did see Butler running with a cushion a few times, but he obviously wasn't a primary on those plays. The team wanted to get the ball out fast to an open guy if the play was there, and that's what they did. Again, it was a reasonable plan given where we are with the offensive personnel. What's more, we're going to continue to see the exact same thing. Now, maybe NO won't play the CBs deep and some of those downfield passes will be earlier reads this week, but it's still going to be read, read, checkdown with the backup stone-golem running the offense.