#2 Thomas Tuchel
After a highly successful spell at Mainz 05, Thomas Tuchel was touted to be a long-term replacement for Jurgen Klopp who departed Westfalenstadion for Liverpool (well, after a brief sabbatical).
Klopp and Tuchel have quite a few similarities as the two employ attacking, free-flowing football. Tuchel eventually succeeded Klopp at Mainz and did pretty well and the same was expected when he moved to the Ruhr to take the managerial reigns at BVB. However, the cerebral manager had a bittersweet spell at the club.
After losing quite a few players to rivals Bayern and other top sides in Europe, Tuchel was left with a young and inexperienced side and it showed as they couldn't challenge Bayern till the end for the title in his two years at the club. They did manage to win the DFB Pokal by beating Eintracht Frankfurt but that wasn't enough as he was sacked a couple of days after the win.
Tuchel was an extremely vocal manager and it was reported that he fell out with the board which led to his departure. Nevertheless, he remains one of best free agents out there at the moment.