#2 Ross Barkley

Another player who Chelsea purchased in January, Ross Barkley is a player that could finally prove his worth this season - provided he stays clear of injuries. The former Everton playmaker, who has been unfortunate with untimely setbacks in the past, has enjoyed a full pre-season and had an extended opportunity to impress new boss Sarri.
As things stand, he is most likely to play the "Hamsik role" for Chelsea in future - as part of a midfield trio, alongside N'Golo Kanté and Jorginho. His stock has fallen significantly in the last few seasons, despite still being such a talented midfielder.
Not so long ago, reports were linking him with £50m moves to all of England's top clubs. Everton had to settle for a mere £15m, as his contract was soon expiring and he wanted a new challenge elsewhere. The ability and world-class potential to be an influential player for Chelsea are still there, but the question is can Sarri be the man who nurtures it to its expected heights?