I wonder if the injuries have fucked him, he got that really bad ankle injury and hasn't looked the same since. You can see from that clip he doesn't have the confidence to take it forward, which is why he does his turn and drops back. That is also why he comes deep for the ball rather than staying up high.
Also I think the team has progressed on and his shortcomings are showing more now. He has a great engine but he just isn't quick or strong enough. He won't have much space so you need someone with a supreme first touch and can turn and get away quick to create a bit of space.