9:56pm: Marshall right-hander Aaron Blair also tested positive for Adderall, reports Conor Glassey of Baseball America. Blair ranked as the No. 41 draft prospect, per BA.

Glassey spoke to a pair of front office executives from different teams, and each believed Gray's usage was a one-time mistake that won't be held against him. A source close to Blair told Glassey that his usage was also a one-time instance.

5:18pm: ESPN's Keith Law reports that Oklahoma right-hander Jonathan Gray, projected to be one of the Top 5 picks in Thursday's MLB draft, has tested positive for Adderall — a stimulant which is banned by the Joint Drug Agreement between MLB and the players' union. According to Law, the test will not result in a suspension, and it's not likely to cause him to slip in the draft.

In fact, in a second piece (this one for ESPN Insiders only), Law outlines a scenario in which this test could actually make Gray more appealing to the Astros with the first overall pick. Law writes that Gray's bonus demands will be lower due to the poor result. One source told Law he expects Gray to sign for a "huge" discount. In that scenario, the Astros could likely sign Gray below slot with the first pick and allocate some of the additional funds to later players without risk of exceeding their bonus pool.

Adderall is typically prescribed as a treatment for ADHD, but Gray did not have a prescription for the drug. In Law's first piece, he notes that more than 110 active players were granted exemptions to use the drug in 2012. Carlos Ruiz's 25-game suspension to open the season was the result of using Adderall without a prescription, he adds. Most teams that Law has spoken to thus far aren't overly troubled by Gray's test, though it does bring his judgment into question.