Scott Taylor, who spent the season pitching at Class A Daytona (high A) was suspended for 50 games "following a positive test for a drug of abuse under the minor league program". I assume that this means that he was using an illegal steroid or growth supplement of some type.
I don't know much about Taylor. He had a mediocre year, though that really isn't the point. I would not be surprised if the Cubs simply released the 20 year old, who is not on their 40-man roster.