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3. Is a Bynum-for-Bosh trade doable under the salary cap?
Yes, but the Lakers would have to jump through a few hoops to get it done. Drew is a "base year compensation" player, which is salary capese for "He recently signed a big contract extension, so he's hard, but not impossible, to trade." To solve the BYC problem, the Lakers would need either to (i) include more outgoing salary in the trade than they otherwise would, or (ii) wait until July 1 of this year, when Drew's BYC status expires.
Let's say the Lakers don't want to wait until July to get Bosh. A trade of Bynum, Jordan Farmar and Adam Morrison would be valid under the cap. In fact, that's the most likely combination of players that the Lakers would send out.