Last night in the post-game, Tanguay was commenting how many tweets, texts, etc came in about people being disappointed that Danny didn't make a big trade. I think that's part of it.
I was/am disappointed, too, but not that he didn't make a big trade, but that he didn't make a trade for a big. And I'm not just talking at the deadline, but in the two month window prior to the deadline, before the injuries, when we had the assets/bodies to spare.
At the deadline, especially due to all the injuries, Ainge either didn't have the assets (to get someone like Gortat)or was acting far too late on someone like Dalembert, and their value had risen out of reach of what we could spare.