On Thursday afternoon, NFL Network and NFL.com reporter Ian Rapoport appeared on the league-owned television channel and announced that New Orleans Saints safety Kenny Vaccaro was going to be suspended four games for a PED violation. He even told viewers that it was for Adderall. What he didn't say was how he knew; he just said sources confirmed. Which is a weird thing, because usually there is a positive test, an official notification sent to the team, an announcement from the league, etc. But not here. Vaccaro and the Saints found out the same way everyone else did: Rapoport's report.
Vaccaro told the Times-Picayune that he had received an initial notification from the drug program, but that was just a preliminary notice that something could be up—a second "B" sample had to be tested before anything became official. That's why the NFL is not even notified until after the B sample comes up positive.
Now, assuming the NFL is not lying here, the league is unlikely to be Rapoport's source. Incidentally, they would be in violation of the PED policy's confidentiality agreement if they were, since Rapoport is an employee of various league-owned media outlets. It doesn't really make sense for Vaccaro or the Saints to leak information of his own suspension, especially when it's not even official yet, so that only leaves someone involved in the drug testing program, which would be a helluva thing. The policy contemplates a range of punishment for a breach of confidentiality, including fines and a termination of services—another reason it doesn't really make sense for the team or player to leak this information. Vaccaro would not comment on whether or not he has used Adderall before (players are permitted to use the medication in the off-season, but not during the regular season).
As Rapoport said on NFL Network, "This is something that is not quite done yet"—because of the outstanding B sample—"so the expectation is it won't be wrapped up before Sunday," meaning Vaccaro will likely play against the Denver Broncos.