5. Marko Grujic
Marko Grujic was very highly rated while at Red Star Belgrade, with The Reds reportedly having to fight of some stiff competition from the likes of CSKA Moscow and Zenit St. Petersburg for his services. Eventually, Klopp made the Serbian his very first Liverpool signing in 2015, paying £5 million for his signature.
Since then however, Grujic has never emerged as a first team regular, and though this is understandable at just 22 years old, it seems unlikely the breakthrough will happen any time soon. Next season, Liverpool's already stacked central midfield of Jordan Henderson, Georginio Wijnaldum, James Milner, Alex Oxlade-Chamberlain, and Adam Lallana will be joined by major signings Naby Keita and Fabinho.
At this point there is no need to write Grujic off as an Anfield bust, but a loan would be an ideal move, and who would be better for the Serbian midfielder to learn from than living Liverpool legend Steven Gerrard?
The 2015 Under-20 World Cup winner enjoyed a strong loan spell at Cardiff last season as he helped The Bluebirds return to the top flight. They, along with Fulham and West Ham, are interested in signing the midfielder.