It's odd with Keita because he presses brilliantly, produces great turnovers and recoveries and also offers elite level carrying, shooting and tackles.
And yet, for reasons I find it hard to put my finger on, he certainly is not the physically dominant, mobile midfielder we seem to be in need of. This isn't simply based on his stature and frame - he's not noticeably weak - but he doesn't cover a massive amount of ground often, or is at least inconsistent with it and is our worst midfielder for being caught ahead of the ball on turnovers. His sprints are also inconsistent.
Looking at the stats in isolation, Keita does seem to be that mobile, physically capable midfielder that we want, but he clearly isn't that. He's more of a languid creator who shows dynamism in bursts. He's always struck me as someone who'd thrive in a 4-2-3-1 as the central part of the three, more of a ten, or in a double pivot with less defensive responsibility.