I've always been a believer that Ainge made the Perkins trade to help rebuild the two positions post Pierce/Allen era. SF, and Guard. He pinned Jeff Green for the SF spot (Pierce), and using the 2012 draft for the G spot. I don't have him going big in this draft, despite the need for a big, rebounding, etc. If he had a top 10 pick, different story.
I believe he's always thought that retaining KG is a must, and everything else would fall into place. He could find that Perkins replacement, just like he found Perkins himself. Ainge has always been high on Bradley, and he knew he had a guard there to fit into the PG or SG role.
I could see him adding one of the Washington guards, Tony Wroten or Terrence Ross, or UNC guard Kendall Marshall. With Green's issues, SF could also be a position that slips in this draft and migh be something Ainge takes a deep look at. Quincy Miller, Jeff Taylor, or Terrence Jones.
As the draft is always a guess, my guess is that two of these players above are Celtics if the picks are kept. Can never count out Ainge trading the pick(s) for the right deal (veteran addition).