#1 Ivan Perisic
Another player who couldn't reach his potential under Klopp is Ivan Perisic. The Croatian winger was signed for €5.5M in 2011 and was expected to flourish under Klopp. He stayed for more than a year at the club showing glimpses of talents which persuaded Klopp to keep him at the club.
On his day, he was the unstoppable winger hypnotizing the opposition defence, scoring thunderbolts from outside the box and whipping in dangerous crosses. But those days were few and far between.
Perisic managed to score 12 goals from 64 appearances before leaving the club to join Wolfsburg for €8M in January of 2013. Though Borussia made a profit in terms of money, Ivan Perisic's signing is considered a flop because of the fact that Klopp failed to explore the huge potential the then youngster possessed.
Perisic now plays a talismanic role for Inter Milan in Serie A.