It's Rudy Gobert. Two other NBA teams have used the same plane he and the Jazz used in the last two weeks (the reported outside incubation period) and the Jazz played in both their own arena as well as games in Detroit, Boston, New York, and Cleveland. Gobert is an excellent and physical defender so I'm sure anyone who drove the lane and made contact with him (or just shared the floor) is going to have some concerns. Considering the close contact inherent in the NBA it's not hard to see how the dominoes have fallen so quickly.
This dramatic move makes me imagine it will be hard for the NHL and eventually the MLB not to follow suit barring a situational change. The NFL is more than five months off but considering its physicality, I can't imagine they will go forward either (barring a similar change). We'll see if the NCAA tournament isn't called; it's already going to be played sans fans and I wonder how it won't be cancelled considering most colleges are also clearing out post haste.
As at least seven players are now known to have tested positive to date, the league (which got out in front of things faster than most) now must ponder whether postponement is a sufficient response or whether the season may truly be over.
22 teams will compete in 8 games (13 west, 9 east) for the usual 16 slots with the possibility of a play-in tournament if any of the lowest seeds can get within 4 games of the 8th seed in each conference. All of the reg season to be played in Orlando, Florida.