He's a headless chicken with no real talent at all.
He has 1 assist, 18 shots with no goals and 13 starts for Hamburg. 18 starts last year between Spurs/Fulham, 9 more sub appearances, 2 goals in 40 shots against Fulham and Cardiff, 3 assists against Villa, Newcastle and Utd. Even the Utd assist was later in the season against an ever worsening Utd. He hasn't scored against anyone good, he shoots constantly with zero quality, he constantly runs around but not as part of the team in a sensible intelligent way, he just runs off like a moron, leaving more gaps defensively in midfield without winning the ball.
He's a classic case of enthusiasm over quality, there is a break even point though where you need some talent. For the ultra attacking way he plays his lack of goals/assists makes him an utter waste.
Harsh to judge him when he has been part of entirely disfunctional teams with no coaching. He is young and needed some instructions and teaching.
Judge him once he plays for a team with a style and identity. Spurs under AVB and Timmeh and Fulham under Magath didn't have any shining lights.
Holtby had a rather screaming preseason and then got shipped out for some reason.