I think he's damn good tracking back, for sure. Especially when covering for fullbacks or getting back to cut out balls into the box. He can be bypassed embarrassingly easily in midfield though. Gets caught square on consistently and is easily passed around. If he played with full intensity and concentration all game long, he'd be excellent defensively. Switches off so often. Those cheap fouls are a feature of his game, and it's not because it's a professional foul; as is often said, it's because he's too lazy to get the right side of his man before tackling him or has switched off and been passed around and someone has run off him.
When he has the ball at his feet, and I know this sounds overly harsh, but I genuinely believe he doesn't really have a clue.
Put him in a better team where the manager doesn't let him think he's the best player on the team, and he'd be a great holding midfielder - even with his current weaknesses.