Russell was literally a drug addict. He came from the hood and had a poor support network.
Murray is a good kid by ALL accounts. His parents are well grounded people and are supportive. He grew up middle class.
Lincoln Riley had one, short conversation with Murray's dad. Everyone around the OU program said that Murray's dad had no contact with anyone. This overbearing father criticism has no basis in reality. He is an introvert, and has done a poor job managing the media. That's a criticism, sure, but it's not the same as imbibing purple drank like Jamarcus Russell.
Vince Young is another guy who had character red flags. One scout I heard write about him, said he red flagged him because he grew up in the hood with a single mother and virtually no male role models in his life. That was his big undoing, he didn't know how to handle the spot light. I don't think that will be the case with Murray since his father and uncle were around pro sports.