It is much more difficult to trade up because you need the assets to do so and by and large Boston hasn't been in the position very often to trade up. The one year (during Ainge/Stevens) the Celtics really had the assets to trade up was 2004 and they not only didn't trade up they used all 3 1st's and drafted pretty well getting Jefferson at 15, West at 24, and Allen at 25. Ainge was actually rumored as trying to trade up to draft Swift, glad that didn't happen.