Wouldn't the Celtics have been better off picking up his option last year, and having him under contract right now? While the money would have been on the books for '17-18, I'd have to imagine an expiring 1 year deal at cheap money for Olynyk would have been pretty easy to shed, and might even net a future 2nd rounder or two.
BTW, while Olynyk is a decent rotation player, I would not pay him were I the Celtics. He can easily be replaced imo. His game is too limited for a long term investment.