It could be indirectly. Some players take care of their parents, grandparents, maybe a more vulnerable family member. Unvaccinated players will also be in contact with more than just other NBA players who are young and healthy.
Being unvaccinated increases the odds of infection and transmission. An unvaccinated NBA player gets it, has no symptoms, plays, gets 5 othe.r players infected, one referee, and another 2 stadium staff members infected, all vaccinated. None of the 5 vaccinated players have symptoms but one player gets his 70 year old grandfather sick and he gets a severe case, the referee gets sick and infects his wife who has cancer, she's on a ventilator, the one stadium staffer who gets it is vaccinated but has Lupus, she dies.
The unvaccinated player later tests positive a couple days later. None of the players got sick or even knew they had it. This is how it spread so crazy to begin with. The people who didn't show symptoms passing it on to more vulnerable people.
It's all odds related. Vaccination doesn't end transmission. But it helps the odds tremendously. Unvaccinated people don't consider the indirect consequences. The unvaccinated covid patients taking ICU beds from non covid patients, for example. People have died because they couldn't get into the ICU for medical attention and procedures that could have saved their lives because unvaccinated covid patients have flooded ICU wards
When you can't consider things other than direct actions and direct consequences, you fail to understand why we're still in a hole place with this pandemic. And you'll make up excuses why pro vaxxers are dramatic, self righteous zealots. But in reality, you're just selfish assholes.