https://twitter.com/ShamsCharania/status/912042340633673730
I find these trade restrictions to be pretty funny. Ron Baker has one too.
There's a good and logical reason for them, though. These players will lose their Bird Rights status if they are traded to a new team. That means their new team cannot go over the salary cap to sign the player and cannot offer full 8% raises, nor a 5 year contract.
That a big deal for some players, thus why the player has trade veto power.
Does that mean we can't go over the cap to resign Kyrie?
Pretty sure we can. In a trade, I believe Bird Rights are obtained by the new team, and he qualifies otherwise.
Correct. Bird rights only get lost (or reduced from full Bird to early Bird) when a player signs a 1-year deal and is traded. I don't know exactly why this is, but I assume it's to prevent shenanigans where a player signs a 1-year deal with his original team, but everyone plans for him to be traded to a specific different team mid-season -- kind of like a delayed sign-and-trade, and then be re-signed the following season by his new team with Bird rights. In the current CBA there would be real incentive for a team over the apron to pursue this, as they are prevented from making sign-and-trades, but this rule carries over from prior CBAs, and I don't know its origin.
Anyway, since Kyrie signed more than a one-year deal before he was traded, there are no issues with his Bird rights. It's only for players on one-year deals. Accordingly, they're allowed to veto a trade to preserve their Bird rights. This happened when we traded for Jordan Crawford in 2013. Originally it was supposed to be Chris Wilcox in the deal, but as he'd signed a one-year deal and would have had Early Bird rights, he was allowed to veto it, and Jason Collins was sent in his place.
Also, player options and team options do not count in terms of contract length before they are exercised, so even though Mirotic has a year 2 option, he technically has a 1-year deal, which enables him to have veto power. This is one reason Ainge signed Zeller to a non-guaranteed year 2 last season, as if it were a true team option, he would have had similar veto power. If Mirotic remains with the Bulls next season because they exercise his option, he will not be able to veto a trade.