I would expect more turnovers from a team that has constant ball movement and passing. Boston has the second highest assists to field goals attempted ratio in the league behind only Utah. Not surprising then that Utah, a team that also prides itself on ball movement in the half court set is 29th in the league in TO/G and the Celtics are now dead last.
Teams that pass the ball a lot are going to turn the ball over more. Could more care be taken with the ball and could a guy like Paul Pierce stop forcing the ball into double teams on the drive, sure. But I for one will put up with the turnovers if it is a by product of excellent ball movement and offensive efficiency.