RB is a more complicated position than one-dimensional stats like assists and tackles can tell a story about. I think Serge gets too far forward too often and leaves too much space behind him for attackers to run into, simple as that. He's also rash with his tackles and ends up giving away penalties. I wouldn't mind him being a second choice fullback to help break down lower tier teams parking the bus, but for the games against the bigger sides, we need someone more defensively alert and conservative, that can help defend a wing effectively in the context of a team defensive unit.