It's a big picture trade, kiddies.
We have 25 mil in cap space... which isn't enough to do anything other than bring back KG, Jeff Green and Bass. Trading Pierce for an expiring contract + lotto pick would be huge for a rebuild. Would have left us with 42 million in cap space to build around Rondo, Bradley, a lotto pick, our two late 1st rounders... and presumably if we traded Ray for OJ mayo and a pick, it would even look sweeter. You'll look back at that, see the kind of talent was available with the lotto pick and probably go, "oh... I get it". Kinda like when Boston tried trading Paul Pierce to the Blazers for an expiring contract and a draft pick... the pick would have been Chris Paul.