As Raees said, Keita isnt a playmaker in the mould of Verratti, but someone with some nice impact passing. They may have other similar attributes, but the biggest one is that Verratti is a playmaker and tempo setter, the heartbeat. Similar to Scholes for us in his later career. Verratti is more complete and can play various roles due to the attributes you mentioned, while Keita is a box to box player, like Fred for us. He will never develop into a Verratti player though, you have it or you dont, and Keita hasnt got that ability. Most midfielders dont have. Keita is a box to box midfielder, but less in the agressive and get stuck in type, more of a dribbling and ball carrier type, but that doesnt make him a Verratti, who is a playmaker and midfield controller, that moves into space, who can sit deep or go forward and join the attack if he likes. Keita dominates games with his box to box game, Verratti may make a tackle here and there or a dribbling, but he dominates by his positioning and metronomic passing, knowing which pass to play at which time and when to pick up tempo or slow down.