That's not actually true -- not sure why people keep saying that.
Memphis, sure -- whether they had a good or bad offseason all depends on Rudy Gay. If he's a stud, they improved. If he's a dud, they did not and may have even regressed.
But the Lakers = added Radmanovic. Player of significance.
The Clippers = get back a healthy Corey Maggette, which could be huge. 20ppg scorer who played in only 32 games last year.
The Nuggets = get back Nene to restore the frontline and added J.R. Smith to plug the OG hole.
I don't think any of those teams made moves to make them contenders, but they all are gaining more than they lost. Not to mention Houston (getting TMac back, + Battier), Minnesota (Mike James + Randy Foye), Golden State (Don Nelson), Utah (get Boozer for a full season after only 31 games, add Fisher for PG help), Phoenix (Amare is back, + Marcus Banks), and New Orleans (Peja + Chandler).
Gonna be tough.