But why would you want both?
I'll concede this - in a vacuum, I'd rather have Turner than Thompson. But this isn't a vacuum.
Over the next three seasons, Turner is due $54 million in salary. Thompson is due $19 million over the next two years, and let's assume that once Thompson leaves, the Celtics use the taxpayer MLE to sign a $5 million/year player for year three. So, Turner over Thompson costs the Celtics an extra $30 million in salary over the next three seasons.
Once Jayson Tatum's max contract extension kicks in, the Celtics will be well above the luxury tax threshold. My best guess is that they'll probably be at the level where they pay $2.50 for each $1.00 over the threshold. That means Turner's extra $8.5 million in Year Two will cost them $21.25 million in luxury tax, and the extra $13.5 million in Year Three will cost them $33.75 million.
So, there's a real chance that trading for Turner over signing Thompson would cost the Celtics an extra $30 million in salary and an extra $55 million in luxury tax over the next three seasons.