First of all, I can't believe anyone would trade 2 top-level keepers with 2 seasons of eligibility left for Tim Duncan for no seasons of eligibility. At best, you might get 2 second-tier keepers, 1 with two seasons of eligibility.
I'd like to see anyone pry Nowitzki out of Ziggy's hands with an offer of multiple players...or Garnett out of DaBods's hands with an offer of multiple players. I know my position: unless I'm getting Nowitzki or Garnett PLUS more players, Duncan isn't going anywhere. Unless I'm absolutely robbing the other manager *AND* getting one of the three folks I see as being the true elite (Duncan, Nowitzki, Garnett), Duncan isn't going anywhere.
Don't know how Ziggy and Dabods feel about their super-elites.
When Duncan's got no more elibigility, though? Well, then I'll just trade him for one of the other super-elites. After all - why not? Why trade for a lesser keeper when the big guns are in the same situation I'm in?
And why would I trade Duncan for 2 lesser keepers if they are only going to have the same eligibility that he is? I'm better off keeping Duncan.
Dabods correctly points out the benefit of me trading Duncan for two keepers of longer eligibility. What you're not answering, though, DaBods, is "Why would the person GETTING Duncan do that - especially next year?" The ONLY answer I can come up with is that the manager doing that is trying to win in the current year, and knows he's in for a long rebuilding process afterward, whereas the player trading away Duncan is looking to the future rather than at the present. If I'm languishing away in 10th place - what is the benefit of keeping an expiring Tim Duncan?
You ask what keeps a manager from tanking? The draft lottery.
What I like about my idea is first, the simplicity, and second, the fact that NO MATTER WHAT, Duncan-Nowitzki-Garnett go through the lottery (at worst) after next season...no matter how they move around. It's known. Managers can plan for that. But if I move Duncan for Garnett today, under our current rules, your planning goes down the toilet. Garnett, Duncan, and other elites will *NEVER* go through the draft. And in my opinion, the draft is better at redistributing talent (and playres) than trades are. In the 2006 off-season, the top three picks in the third round are likely going to be Nowitzki, Duncan, and Garnett in no particular order. And they'll be kept for the maximum 2 off-seasons. Those three managers with the top 3 draft picks will be smiling - because, most likely, they'll have the weaker sets of keepers going into the draft, and will have a strong set coming out of the draft. And the people who are competing for the championship are the ones who are more than likely picking at the end of the draft...and its likely that they've got other reasonably strong keepers, since they WERE competing for the championship. The top teams generally have stock-piles of talent - which is what makes them the top teams. And almost always, they're looking to trade 3 Reggie Millers for one Kobe Bryant. They're not looking to trade one Kobe Bryant for 3 Reggie Millers. Their roster is too deep to allow that.
Essentially, one great is worth several very goods, but usually, most people would rather have the one great. The only reason you'd rather have several very goods than one great is because you're looking to rebuild.
Again, take my case. What good does it do for me to trade Tim Duncan for Dwayne Wade, Kobe Bryant, and Lamar Odom? I can only keep two - and even that would mean I'd need to drop Rashard Lewis or Steve Nash. If, at the end of the season, I could trade Steve Nash, Rashard Lewis, Drew Gooden in exchange for Kevin Garnett, why would I NOT want to do that? Even under my scenario - where at the end of the year, Garnett *AND* Duncan would be gone? A Garnett/Duncan combo could easily be devastating. I'd take that gamble for a year, and rebuild afterward...simply because I have confidence that I'd field a reasonably good team even if I have a late draft pick. But why would YOU make that trade at the end of the year? You wouldn't.
Elite players for foundations for teams. It's unavoidable.
In fact, there's only 1 reason for a person to drop an elite-level player earlier than his final year - because that manager has the number one pick, and will use it to lengthen the time he can keep his superstar. That's the only real abuse that I see.