I think you should google the Steelers history of run-ins with the law. There never was such a thing as "the Steeler way" if you believe that means they had a roster full of guys with no character risks. Shooting at police helicopters on the Ohio Turnpike, putting together a multi-state prostitution ring, having pounds of marijuana in the trunk of the car when pulled over by the cops, Bar fights and more; these are all part of the Steelers players' history during the period when most folks claim there was a "Steeler way" as far as character.
Shooting at the helicopter was Ernie Holmes who was in court to answer for it and evidence was presented that he had severe mental problems issue resolved through legal channels. The day the prostitution story broke it also contained the news that the steelers released this guy can't remember his name. The dope in the trunk was from an arrest in Rockwall Texas of Morris who was either off the team at that time or shortly there after. Many of these guys were given a second chance think stonio for example but if unable to get it together they were gone.
The big issue with the guy that tests positive for drugs is the suspension and the accelerated suspension program for these idiots. This guy could end up with a season long suspension prior to his rookie contract being over and that just ruins the value of the pick. He may already have strike one and his next could be his second offense. The next biggest issue is the fact that this stoner knew the test was on the way and still was unable to do with out the drugs. That could indicate a serious dependency issue in spite of the popular claims that the drugs are not addictive. Either of those two issues alone could spell the early end of a football career. There is however a third to consider, and that is the lack of decision making skills and dedication to his craft that is implied by his choice to remain stoned.
The guy maybe gifted with lots of talent but his choices could have him out of the league before the first contract is up, not a good risk.
A team would need to really look into this guys background before taking him over a lesser more reliable player.