During a typical NBA game, Gobert would be setting numerous picks/screens and every time he does so there would be contact. I would think the transmission could occur in the exchange of sweat that occurs when one player contacts another. There would have been plenty of contact between him and the opponents during the game, and not just on the guy covering Gobert on defense. The ball itself is covered with the sweat of players touching it and often has to be wiped by referees during games. Every time Gobert touched the ball, he likely left his residual sweat on the ball, to be transferred to the next player handling the ball. He may well have infected each and every player whom he played against, after he himself was infected.
NBA games are not played, nor are intended to be played, in a sterile hospital like environment. That is why they suspended games immediately after the Gobert positive test.
