Firstly Hayward has to be ruled out by doctors for the entire season, through the NBA finals. So he’d have to require recovery time of a minimum of 8 months. While that’s possible, I’m going to hope he has the potential for quicker recovery than that.
Secondly, the Celtics aren’t going to go into the luxury tax for a replacement, so the max we will sign a player for is $9 million (assuming we are awarded the exception to begin with).
Thirdly, we can also use it to trade for a player who is in the final year (including options) of his contract.
I think the best replacement we could get in the free agent market is Alexi Shved. With $9 million to spend, we could certainly afford to buy him out of his final year in Russia and give him a raise from his current salary of around $3 million.
The most interesting players we could trade for are Jabari Parker and Aaron Gordon. The cost might be steep, but Parker is certainly available, and Gordon could be too for the right draft picks.
But mostly I want to hear the Hayward will be ready to return in late March or early April. We can get to the playoffs without him, and probably still nab a top 4 seed.