Those guys - Gasol, Rondo, Kobe - they were actually picked by Memphis (Vancouver, actually), Boston and LA. The trades were already in place before the draft, it was the pick that was traded, not the players. Due to the CBA rules, they can only make those deals official after the trade, so formally they are drafted and then traded. But it's just formally. It was Ainge that decided to pick Rondo with that draft pick, not the Suns GM .
Btw, the Celtics were very interested in trading for that Atlanta pick to get Gasol. Unfortunately, the Hawks prefered SAR over Boston's 2 lottery picks (that ended up being Joe Johnson and Derrick Brown). It'd have been interesting to see how far a Pierce+Gasol core could have gone.