I think the lack of free throws are a feature of Brad's system.
I'm not exactly sure how or why, but it's been a consistent trend over the years, with the lone exception of IT, who garnered tons of free throws two years ago during his peak season.
I wonder if it comes as a result of the emphasis on always finding a better shot. It seems to me that maybe getting to the free throw line, sometimes, is a matter of deciding to force a shot up against pressuring defenders and pressuring the refs to call something.
If you're always passing the ball to somebody else that might be more open than you, that's generally a good thing -- open shots are better shots -- but it might also result in significantly fewer opportunities to draw contact.
I don't know. Open shots are good and the Celts generate more than almost any other team in the league. But free throws are vitally important as well, especially when your jumpers aren't falling and you want to maintain a lead.