Limiting Gan Guoyang's scoring to 30 points or less was already a tremendous success for any team.
As a center who excelled in both offense and defense, Gan Guoyang contributed a large number of rebounds on the defensive end while also guarding the hoop, and on the offensive end, he could easily rack up more than 30 points, and even explode for 40, 50, or 60 points, which was quite terrifying.
This wasn't the 50s or 60s when the league had many part-time players who had day jobs, drove taxis, fixed plumbing, installed air conditioning, and then wore jerseys to play at night.
Against someone like Chamberlain, a physical freak who transcended his era, these players stood no chance, watching helplessly as he scored 40 or 50 points and grabbed 20 or 30 rebounds per game—Chamberlain didn't even need to rest and could play the full 48 minutes.
