Well, Jordan Henderson is very good at receiving the ball, turning around and then passing it sideways. Xabi Alonso, to name but one, had complete control over the ball in on touch whereas Henderson takes two or more. That is one of his weaknesses.
Obvoiusly too hard for Achterberg. Like someone above said, none of the goalkeepers since, well forever, have actually improved while staying at Liverpool. That is a problem.