The Boston Celtics Summer League starts on Friday, July 6, 2018 versus the Philadelphia 76'ers. We already know that Jayson Tatum will not be participating, and that totally makes sense. He has nothing to prove after the season he just had.
Daniel Theis will almost certainly not participate. He is still recovering from meniscus surgery but may eventually play for the National Team later in the summer. Abdel Nader underwent right wrist surgery recently and is out of action for several months.
Guerschon Yabusele saw little playing time for the Celtics this past season and can certainly make use of the additional floor time.