#2 Ciro Immobile
It is an enigma how a player of Immobile's caliber failed to develop under a manager like Klopp. He is now a prolific goalscorer for Lazio, finding the net with a certainty that puts his Borussia career to shame. He scored 76 goals in 104 games for Lazio, the evidence of his talents. But for Borussia, he managed just a 10 in 34 appearances.
The Italian center-forward was expected to be a regular scorer and the target man when he joined from Torino for €18.50M. That was the year Lewandowski left Borussia, and Immobile was presumably his replacement. Under Klopp's high pressing 'heavy metal' style, he never settled.
He spent only a season at Borussia Dortmund, as he rarely found the back of the net. He was sold first on loan and later permanently to Sevilla for €11M.