I just don't think he's good enough really. He looked decent in a very tight, compact defence with two organised banks of four, but two tight banks of four aren't conducive to expansive football, as Burnley are showing.
If we have any desire to play a bit more open you need your centre halves to be mobile and have pace and ability get around the back line if your full backs push on. I just don't think he can do that and looks lost when he's left isolated. Obviously love him to come good but I've not seen much so far to suggest he's anything like the standard you want to build the spine of your team around.