The Bulls operate in such a shroud of paranoid secrecy that their moves come across as surprising even though in retrospect they shouldn't have been. After publicly steadfastly saying they would effectively stay the course, with reports seemingly adding to that consensus (though not exclusively), the Bulls traded Luol Deng to the Cleveland Cavaliers for picks and financial benefits.
In a way, it had to be done. Once Derrick Rose went down, this 'last stand' season was over, so all decisions then were to be about future years. And based on their negotiations this past summer, it was clear that the Bulls and Deng were simply too far apart to think a new contract would be likely. After the trade, Adrian Wojnarowski reported that Deng turned down a 3 year, $30m extension to remain a Bull beyond this season. KC Johnson said the Bulls offered a 4 year deal at that same rate as well, though technically that would have to be offered in the offseason when Deng became a free agent.
With the reported asking price from Deng's people being $15-$16m, using Josh Smith's $14m deal signed last offseason as a benchmark, you can see why talks didn't progress much. These are both fair ends of the spectrum, so could the Bulls have eventually met Deng somewhere in the middle of those figures? Perhaps, but I'm not sure they even wanted to pay Deng for four more years even at 12 or 13 million, given his age and accumulated wear and tear. Luol Deng put in that work to become an all-time great Bull (and we'll have more on that, of course), but the idea is to pay for future performance, not past. And though Deng could very well have an extended prime given his skillset (and I could talk myself into liking a 4/$48m deal for sure), it certainly would've been a risk to keep him at any seven-figure amount.
And at that point it was also a risk to wait and find out. Letting Deng walk (or get practically-nothing in a sign/trade this offseason) would've been pretty disastrous, and credit to the Bulls for being proactive in figuring an extension just wasn't going to be likely. It's not something they're often known for, but the Bulls were aggressive with this considering an alternative was looking like merely 'letting it play out' heading into the offseason.
So the Bulls certainly got not-nothing for Deng. But what did they actually get? The picks are protected to the point where it may not even get them an extra first-rounder. The possible extra first is from Sacramento, but is top-10 protected for the next 3 years (top-12 this year, and that's not happening) after which it doesn't become unprotected, but instead becomes a second round pick.
That and a 2015 swap (also lottery-protected) with Cleveland, 2 second rounders...there isn't much in terms of assets, here. And using the term 'cap flexibility' is kind of a misnomer, since at worst Deng was going to be a free agent and be off their cap next season if not re-signed.
But they do save pure cash. A lot of it. Based on calculations of their payroll and tax obligations prior to the trade, after waiving Bynum (oh, right: they're gonna do that as to not guarantee the rest of his season's salary) the Bulls will save $20.6m this season. Dipping under the luxury tax also means they'll get the yearly payout from New York and other high-payroll owners which is another $2-3m.
It's not exclusively cash, there is 'flexibility' gained here as well by getting under the tax this season. Essentially, it keeps them out of a repeater range for a few seasons. The Bulls paid the tax for the first time ever last year, and if they had done so this year their next tax paying year (given it was in the next 2 years) would've made them a repeater. Assuming that they were very likely going to be under the cap (and thus far under the tax) this offseason, you can think of this gained flexibility as not paying the tax this year 'affording' them to pay it in 2015-16. It's like, oh, trading Kyle Korver for a trade exception that may get you another player in a year.
This is what made this Bynum contract a unique opportunity that wasn't available from any other team at any other time this season. Not mere cap flexiblity or perhaps a young player on a cheap deal, but immediate savings. KC phrased the Cavs including these picks as 'meeting the Bulls demands', but I'd have to think it's the Bulls that blinked: the deal had to be done by today for Bynum to be cut before his contract was guaranteed.
We've kind of begrudgingly accepted (via Stockholm Syndrome) that the Bulls will always behave like a mid-market team, so making this particular deal to under the tax threshold is important. Getting that much money (plus some more Derrick Rose insurance payouts!) is important too, especially if it makes Amnesty for Carlos Boozer more palatable this offseason. There's also the tertiary benefit of simply making the current team worse, and thus having their own pick be more valuable in the upcoming draft.
But overall, this isn't much return for Luol Deng. Again, we kind of accept this at this point, but it's possible to have made a deal where better assets were gained instead of savings. Making any deal now is something the Bulls should receive credit for even doing at all given our expectations of their deliberateness. But given the return we probably shouldn't have been surprised.