In addition to the many salient points other posters have made, it's extremely difficult to structure a sign-and-trade that actually fits under all the various salary cap rules AND pays Pekovic large sums of money.
Because Pek would be getting a raise in a sign-and-trade deal, he's subject to the base-year compensation rule. This means that his outgoing salary is treated at only 50% of what he's getting paid for purposes of what Minnesota can take back in a trade. (This is one reason Bogans is getting paid so much by us, since his salary only counted 50% for what the Nets could take back). Meanwhile, we would need to send out enough salary to a) only take back 125% of what we were taking on and b) fit under the hard cap.
The most Pek can be paid this year is $13,701,250, per maximum salary rules, which is presumably what he's asking for. This means that he would count as $6,850,625 worth of salary sent out. In this case, Minny could only take back $10,275,938, However, to take on $13,701,250, the Celtics would need to send out $10,881,000, so it won't work, unless the Celtics are also taking on and sending out additional players. Also of note, we don't have anyone making those precise salary amounts.
Now, what does work salary wise is Pek+Cunningham for Humphries+Sullinger, as that leaves the C's a couple hundred thousand under the hard cap while meeting all the salary matching rules, but that trade can't happen until September 14th. Humphries+Crawford sends Minny back too much salary, as does Hump+Bradley. Pek+Barea allows Minny to take back more, but also means we're taking on more salary and run the risk of the hard cap. Still, something like Pek+Barea for Hump+Crawford+Sully or Hump+Bradley+Sully works.
But we can't trade Humphries with other salaries for another 5 weeks, and he's the most logical player to make salaries sort of match (although Green+Bass+anyone on a rookie deal for Pek+Barea works). Still, these deals now become pretty complex, and add an additional shooting/combo guard to our roster, and it just seems unlikely that there's anything that will make salaries match and make sense for both teams. It's a topic to revisit on September 12th, or whenever it is we can trade Humphries, but probably not much earlier than that.
Also, base-year compensation is why Minny can hold pretty firm. The only teams with cap room to sign him outright are Milwaukee and Philly, and if they wanted him he'd be signed by now. Otherwise, for Minny to lose Pek it has to be a sign-and-trade, and those are going to be very complicated for any team to make salaries match and provide Minny with compensation worth having. And if Pek chooses to not sign this year, Minny retains their right to match any offer he gets next year, but he no longer can leave via a sign-and-trade, so his leverage will go down. If they don't reach an agreement by the end of camp, I'd expect Pek to sign his qualifying offer, play out the season, and test unrestricted free agency next year. It's pretty unlikely Minnesota will make a desperate move in this situation, since Pek is the one with less leverage.
