Thomas Tuchel's appointment as Chelsea head coach a year ago has always been laced with intrigue.
Regarded by some as "complicated" and a "perfectionist", the German was described by Borussia Dortmund chief executive Hans-Joachim Watzke as "a difficult person" and Tuchel had fall-outs at Mainz and Paris St-Germain too.
So why would Chelsea, a club where managers do not last long and player power has seen a few off in recent times, turn to him?
Why too would Tuchel, who was initially given only an 18-month contract at Stamford Bridge, take a chance on Chelsea?
Because, as Watzke also said, the 48-year-old is a "brilliant coach".