The 2017/18 campaign was one to forget for Borussia Dortmund as they were forced to endure some of their most turbulent times in recent memory, finishing fourth. Given its topsy-turvy nature though, it will unfortunately also be one that lives long in the memory.

New head coach Lucien Favre has the advantage of his predecessors, Peter Bosz and Peter Stöger, setting a low bar ahead of his debut season in charge. Banishing the lingering memories will be one of the Swiss' top priorities and BVB's transfer dealings have already sent the right message. 

Read more: Borussia Dortmund confirm Axel Witsel signing

Witsel the jewel in the crown

Marwin Hitz will provide real competition for compatriot Roman Bürki in goal, while Abdou Diallo, Marius Wolf and Thomas Delaney all come on board having proven themselves in the Bundesliga with Mainz, Frankfurt and Bremen respectively.

However, their latest signing, Axel Witsel, could prove to be the biggest coup of them all. The 29-year-old caught the eye with a string of impressive performances as Belgium finished third at the World Cup and sealed his Dortmund deal in time to join up with the squad at their Bad Ragaz training camp on Monday.

"After the World Cup, I was determined to transfer back to Europe,” said Witsel. "I am really happy and also proud that I will soon be able to play for BVB. I didn't have to think about it for very long after our first discussion because Borussia Dortmund is one of the best clubs on the continent in my opinion. I honestly cannot wait to run out in front of 81,000 people.”

Comfortable in possession, adept at breaking the lines with pace or a pass and tireless in his off- the-ball approach, Witsel embodies qualities Favre favors, which should see him slot straight into BVB's starting line-up.

A few too many in midfield

As a result, the Belgian's arrival could also speed up Dortmund's clearing out process given the excess of options Favre has at his disposal in the center of the park.

Newcomers Witsel and Delaney are set to compete with Mahmoud Dahoud, Mario Götze, Shinji Kagawa, Julian Weigl, Sebastian Rode and Nuri Sahin for one of three starting berths. 

"We are a bit overloaded in certain areas,” admitted Head of Professional Football Sebastian Kehl. "The next few weeks will be decisive. We want to make sure we have a quality throughout the squad.”

Dahoud and Götze have both featured heavily in pre-season, suggesting Favre is looking to breathe new life into the careers of both players and, while Weigl has been linked with a move, Rode and Sahin need to seek pastures new if they want regular first-team football.

Read more: Mario Götze is facing another decisive season

Favre's pre-season experiments

At Borussia Mönchengladbach, Favre favored a 4-4-1-1 formation. At Nice it was the 4-3-3. If early indications are anything to go by though, it appears as if Favre is looking to employ the 4-1-4-1 system in his new role, allowing him the flexibility to switch to either of his preferred formations over the course of an encounter.

No matter the system, Favre's style of play demands an exceptional work rate, as the technically gifted work off a midfield anchored by an intense and united pressing effort. At first look, Witsel appears to be a perfect fit.

The 96-time Belgian international's vision and playmaking ability should not only complement the more defensive-minded qualities of Delaney in midfield, but also provide a more creative spark in the center of the park - something BVB were sorely lacking at times last season.

A big-name signing is a clear signal of intent from a side desperate to halt their decline. Now it's up to Witsel and Co. to build on the momentum as they look to turn a new leaf when their season gets underway.