1. david robinson gradually entered the late stage of his career, and the deterrence at both ends of the attack and defense was declining. Moreover, the strength of other inside players in the team is not good, such as Wilpudu, so the Spurs urgently need new people to strengthen the inside strength.
Duncan is very clever. During his tenure at Wake Forest University, Duncan won the honors of "Best Athlete in Atlantic Coast League", "Naismith College Player of the Year" and "john wooden" successively. At that time, it was generally considered to be the best candidate for the top scholar.
3. I will be injured last season, and the Spurs' record is terrible, but the next year will be cloudy and win the first place.
To sum up, the Spurs chose this new cornerstone player and opened a new era for the Spurs.
I hope my answer will satisfy you.