The Warriors only have the MLE to offer to Wilcox and I don't think Wilcox is interested in that, as from all indications he is looking for around 6~7M starting.

More likely there will be a trade if the Warriors are going to get Wilcox, but I am not sure Seattle is interested in Murphy - our prime trade bait - since their financial status is insecure at best.

There's a significant problem with any sign and trade of Wilcox.  Namely, as soon as he's signed, even in sign and trade he becomes a BYC player.  Unless we can make the math such that 2.9=0 we couldn't swap Murphy for a resigned Wilcox even up if both teams wanted to.  The deal would have to include other players--most of whom would have to come to GS-- or some third party who can absorb a cap hit.  Other players Murphy for Wilcox and another player could happen, but it's not clear who else the Sonics want to part with to make it attractive to them or who else from our squad similarly makes it an attractive deal for them.  

Maybe Mullin hasn't officially contacted Seattle because he understands that the math is complicated.  I doubt this is really his excuse, but perhaps he realizes that the rumors are fantasy filled and that a real deal going to involve a lot more than that because of cap considerations anyhow.

The real gamble is that Stern falls asleep and doesn't notice that we've offered a contract that violates the salary cap.  $21 over three years is over the MLE.  Seattle offered $19 over three because no one with only the MLE can beat this. We can't offer fewer years under the CBA and Wilcox has stated that he doesn't want a longer deal at that price.  Your proposal doesn't work under the present rules.

Your trade further can't happen. The resources we have for Wilcox are limited because if he signs for a sign and trade, BYC clauses come into play and it means the deal has to be big, involving more players or more teams. Straight up, we can't swap salaries for him.  If he doesn't do that, there's no way we can get him unless Seattle decides he's not worth even the MLE. They've already offered him that and he's turned it down, so that's unlikely as well.
 

The Knicks offered the full MLE to Jeffries.  It looks like a bigger deal because it's for a full 5 years, but we could offer exactly the same contract to Wilcox.  Problem is that he wouldn't take it.  Jeffries valued the stability of the modest starting salary of $5.2 million brings you.  Wilcox wants a bigger deal.  He wants to be making twice that in short order.

The available ways to do a sign-and-trade are to either keep the contract low (which won't happen) or have the total salaries moved be in the neighborhood of 12-16 million going each way.  We're talking Foyle and Murphy or Murphy and Pietrus (though I don't think he's valuable and would ship him out for a broken crescent wrench) and Zarko or something in that salary neighborhood.  We'd have to take back something other than Wilcox too though and it's got to be a pretty big salary.  Fortson might work--I've not really calculated the numbers, but otherwise Seattle isn't loaded with contract they're trying to move for cap situations.  Fort comes off their books at the end of next year so he's probably more valuable to them for his cap space than as a tool to get a player they don't really want like Murphy or Foyle.

Otherwise, the option is to involve another team that can broker the deal divide the salary differential into a team that's not capped.  These teams are few and far between and they'll want something of value (eg picks) for use of their cap space.

I can't really blame Mullin for not getting these things done now, though signing Murphy and Dunleavy when he did was just dumb.  It was dumb at the time and hasn't gotten any smarter with the passage.