The unofficial NBA trade season typically doesn’t open until December 15, the day on which most players become eligible to be traded. Why? Because the CBA prohibits teams from trading players whom they signed as free agents during the offseason for three months or until December 15, whichever is later. A few can’t be traded until later in the season but that number is usually much smaller (17 this year) than those who can be traded starting on Dec. 15 (85 this year). Don’t expect a lot of trades to happen early after December 15 but there are likely to be a few with the amount growing rapidly as the Feb.