One of the biggest disappointments in the Premier League so far this season has been Timo Werner.
The German forward was one of the most sought-after players in Europe last summer following some brilliant displays for RB Leipzig.
He scored 34 goals in 45 games for Leipzig in the 2019/20 season to cement himself as a world-class striker.
It was Chelsea who won the race for his signature, with Werner joining for £47.5 million.
But Werner has failed to live up to expectations.
He's scored just eight times in 23 games for the Blues so far this season.
The German striker has produced some anonymous displays and has also been guilty of missing some guilt edge chances.
But why is Werner not replicating the form he showed at RB Leipzig?
It makes for fascinating reading and you can view the thread below...
He begins: "At Chelsea Timo Werner has been primarily used as a winger contrary to his striker position at RB Leipzig. But the problem is not only Werner's position but also his role at Chelsea as this thread attempts to unveil."
Bergmann writes that Werner thrived at Leipzig by occupying a central role in the space between the defence and midfield.
But at Chelsea, by playing out wide, he has been unable to take up these positions.
The Blues play a lot wider than Leipzig did and that is not playing to Werner's strengths.
When Werner does make runs in wide positions, he is often isolated and Chelsea are unable to utilise the space he has created.
When Werner played as a striker for Leipzig, his runs in behind created chances for both himself and teammates.
He impressed when given that exact role for Chelsea against Southampton, scoring twice and recording an assist.
In Bergmann's view, the most important issue is Werner is unable to utilise his ability to counter-attack.
At Leipzig, Werner was given the freedom to take up positions where he could hit opponents on the counter.
He is unable to do this at Chelsea because he is required to do a lot more defensively.
It's clear that Frank Lampard's tactics are not playing to Werner's strengths.
He desperately needs to start getting the best out of Werner, who is arguably Chelsea's most dangerous player.
And it starts with playing Werner in his most effective position: as a central striker.