Why it makes (reasonable) sense to do this trade:
Celtics: it would bring the team salary back under the taxable threshold, resetting the repeater tax.
Mobley would bring elite cover for Porzingis in case of injury or rest and still only 22 years old, he brings longevity to the core group.
Cavaliers: The Cavs are really on the clock to impress Mitchell enough to re-sign long term and offensively Mobley is still a work in progress. Bridges is in his prime, selfless and helps spread the floor.
Nets: Brown is locked up to a five year deal and although weaker on defence, is an upgrade offensively. Like Bridges there maybe be more to Brown without the shadow of Tatum.
Although LaVine is a health risk, hes a huge upgrade over Simmons.
Bulls: This roster is dying for an elite passer, although hes far from perfect, Simmons is just that. With only one year left on Simmons deal, the trade at least takes LaVines albatross (3 year) contract off the books.