Baseball already have breakouts and games being rescheduled
Yeah, but baseball isn't quarantining. If the NBA players follow "the rules" and don't go to strip clubs and what not, then the only thing they need to fear is a Disney employee coughing on their food.
Baseball on the other hand, their players are free to do whatever is allowed in their communities, they are staying in whatever hotels are available and they are having to go through airports and deal with airline employees who are exposed to thousands of people a week (chartered flights are still chartered via an airline).
I think the NHL and the NBA are going to succeed in their restarts. I think the MLB is going to have a couple serious outbreaks to the point that they might have to figure out how to write an entire team off and the NFL... unless they figure out a "bubble" scenario, I don't know how it will work.
Given that the only areas with enough legit baseball stadiums available to house the MLB are in Florida and Arizona are also waaaaaaaaaay too hot to play outdoor baseball in the middle of the summer, I can see why the MLB didn't view a bubble as realistic (and that is before Florida and Arizona became Covid capitals), the NFL does not have an excuse. There are football fields that yield standard dimensions in hospitable climates all over the country. If they're paying attention to the MLB and their status on the brink of disaster, I would hope that they are beginning to look for some isolated options.