There's a few posters who keep saying this, and I'm one of them, but when he's been on the pitch he's, mostly, been very good for us. I'm trying to work out what's happened with him, he was picked a lot at the start of the season after all. I reckon Klopp's decided that he can't carry two players who, physically, aren't quite up to it (in comparison to the athleticism of Fab, Gini, Milner, Henderson) and so he won't play Thiago and Keita in the same 11. And Thiago, for relatively obvious reasons, is preferred. I also suspect Keita's injuries have taken a toll on him physically, perhaps he's always been quite slow after the initial 5/10 yard burst of acceleration which he's still got in him but I wouldn't be surprised if he's lost a little bit in top speed and also lost something of his initial acceleration.