He used to be absolutely quality, top 5 strikers in the world easily.
I think there's a number of reasons why he isn't able to get near the form he once had. With Liverpool, he was the main focal point of their attack, everything went through him, and as much as I hate to say, a midfield of Mascherano, Alonso and Gerrard was one of the very best in the world at that time.
Injuries have no doubt also taken their toll on him, he's lost a fair bit of pace and doesn't have anywhere near that confidence any more.
What price would you pay for him these days? At Everton you'd surely be livid if in some crazy situation we paid even £10m for him.