The Phillies just finished a three game series at home against the Miami Marlins, who have had twelve players and two staff members test positive for COVID-19. The Phillies were slated to play two games at home against New York, and then play two games in New York against the Yankees on Wednesday and Thursday.
The Phillies players and staff will presumably be undergoing testing, and I suspect they will do both the over-the-counter type instant results tests and the more accurate tests that get sent off to the lab for processing overnight. The instant result tests could potentially give the team an idea as to whether and to what extent anyone was potentially infected during the series against the Marlins.
With Philadelphia and New York being 90 miles apart, the travel situation is such that, if MLB wants to get the games played, they could theoretically have the Phillies travel to New York on Wednesday and play a pair of doubleheaders there, if they don’t want to play at Citizens Bank Park until there’s deep cleaning done there. Of course, if there is a significant number of Phillies players who end up positive, that solution wouldn’t be viable — and even if Phillies players don’t test positive, MLB could end up pulling the plug on the season anyway due to the health risks.
UPDATE — Per Ken Rosenthal, all the Phillies players are reporting to the stadium today, getting tested, and then returning home. The results of these tests will probably give us a strong indication as to whether MLB is going to continue playing or not.