4. Loan: Fikayo Tomori

Fikayo Tomori has improved leaps and bounds ever since he joined Derby County on loan last season. He was an absolute rock at the heart of Derby's defence. He looked like a leader and was often seen taking responsibility for the backline.
Tomori as a defender has all the right qualities. Being a good header of the ball, Tomori handles set pieces in a great manner. Since Lampard played a quick pressing style last season, Tomori looks very comfortable on the ball and can bring the ball out from the back.
While some would argue that Tomori deserves his first-team opportunity, it seems that a loan move to a Premier League club is ideal. At the moment, the Chelsea squad is loaded with a plethora of centrebacks. Moreover, most of the center-backs at Chelsea are experienced professionals. Even if Tomori stays at Chelsea, he would be on the bench more often than not.
Since his past season was on loan at a Championship club, spending a season at a Premier League side would enhance his development even further and make him ready to play for Chelsea.