There are genuinely nice people, but by definition, a nice guy is not genuine. His niceness is manipulative and transactional at its core.
He avoids conflict by showing up as whatever he thinks will get him most accepted by the group. People have an unease around him, and distrust of him, because he is insecure, always attempting to be what he thinks others want him to be, instead of taking a stand for who he actually is, and for what he actually believes. Typically he has the attitude of, "I'm not like the others," when, in reality, he is exactly like the others, many times worse than the others, he just hides it under a veil of being an ally. He prioritizes others needs over his own as a way to manipulate, not out of a genuine sense of care. When he gets what he really wants, he is quick to discard the people he used to achieve his goal.
I believe that's Russ. I believe that's why he has left a trail of team mates and coaches who don't seem to like him much. They won't speak ill of him, but it's pretty clear that they don't have the kind of deep friendships that they have with the rest of the team.