The thing is, moving Stoner gives Anaheim cap space and reduces their payroll. The cap space is an asset which they get immediately and can use at their own will, while the lower payroll allows them to do that. The other team would get draft picks at the cost of two years of cap space and money. Those picks aren't close to contributing in the next three years, nor are they guaranteed to be anything worth having. You can hit Faulk, Aho and Rask - or you can hit Alt, Dalpe and Hagemo.
What are the chances of the former happening? Close to zero. Heck, even the chances for one of the second rounders to hit is low - let alone more than one.
9/30 2011
10/30 2010
12/30 2009
11/30 2008
6/30 2007
=48/150
I went through the five drafts from 07-11 and counted the amount of second round players who have contributed in the NHL (criteria: ~100 games, also those who are contributing now but don't have enough games under their belts, such as Jacob Markstrom and Brian Dumoulin). Now, the probability to get one seems to be around the 32% mark. That looks good on paper, but then... guess how many of those players are/were players who got their chances but never stuck around, or those who bounce between the fourth line and the pressbox? This is just my opinion, but if you go through the data yourself, I don't think your score will differ too much from my 13. If we combine these numbers, the likelihood of getting a decent top 9 forward/5D or better/a capable goalie from the second round is around 23%.
From that trade offer, you get three shots at getting a contributor from the draft. On the other hand, you could get a prospect, a more known commodity. How likely is it for a good prospect to become a contributor? Much more likely than a pick, that's for sure. And that counts for many, many GMs. They want bang for their buck, not magic beans. In this case, it means that one of your high end prospects is what it would likely take to get Stoner shipped out.