But to many Owls fans, 28-year-old Börner is still largely shrouded in mystery. We asked Tom Nuttall-Jones, senior league analyst of 2.Bundesliga for Football Radar, what Wednesday supporters should expect from the former Bielefeld captain.
Wednesday have been looking for a leader in defence - is Julian Börner their man?
Leadership is perhaps his strongest quality. The Arminia defence, whether they have played with a back four or occasionally a back three, has always started with him in recent seasons, and he is always the one in charge.
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What style of defender would you say he is?
Arminia definitely like to play out from the back and he is certainly comfortable doing so. While he was not the most aggressive or cavalier of their defenders bringing the ball out, he had no qualms stepping out of defence and picking a pass. He might struggle a little bit more on the average Championship pitch though!
He was a Germany youth international - why hasn't he ever made the step up to Bundesliga football?
While he could definitely have been counted amongst the strongest 2.Bundesliga centre-halves in the past two or three seasons, his club were pretty inconsistent during that time. Arminia went from battling relegation in 2017 to finishing fourth in 2018, meaning he was either off the radar of top flight clubs, or perhaps holding out hope of achieving promotion with Bielefeld.
He also had one or two spells of shaky form in the midst of strong overall campaigns, which might have cast some doubts. Like in England, only a few players make the move to the top flight via transfer.
What are his strengths and weaknesses?
His strengths would certainly be his leadership, dominance in aerial duels, goalscoring from set pieces, bravery in making tackles and his reading of the game. In terms of weaknesses, he lacks a little bit of pace and has been caught out either through that or very occasional lapses in concentration.
He was club captain at Arminia Bielefeld - what sort of character is he?
As mentioned above, he is definitely a strong leader in the dressing room and on the field. So much so, that while there is no doubt that striker Fabian Klos is the club's talisman and icon for the fans, there was little fuss made when it was thought better to move the captain's armband from Klos to Börner.
He's 28 and this will be his first move outside Germany. Is there a feeling that this is a risk for Börner?
Not particularly for the player himself. Of the several players to have made the move to the Championship from Germany in recent seasons, those who have not been as successful have found it very easy to find a move back within a couple of seasons, even to their former club, but at least to one at a similar or better level. A move back to Bielefeld might be a stretch for Börner however, as they were very unhappy with him deciding not to stay and he was left out of the squad for their final matches of the season.
How much of a hole will his departure leave at his current club?
At present - pretty vast. They are yet to look for a replacement and while the club's finances are pretty healthy, Börner left on a free so it's not clear whether they will be able to get someone in of a similar level. He really was one of the strongest defenders in the division and on several occasions he has been at the heart of them holding the strongest defensive record in the league. His departure also took them a little by surprise as all reports suggested he was planning to stay before Wednesday showed their interest.
How do you expect him to get on at Wednesday?
I expect Börner to do well almost regardless of how well Wednesday get on this coming season. In the past three campaigns in the 2.Bundesliga, Bielefeld have battled relegation, flirted with promotion, and then finished mid table. Börner's overall consistency has shown through and was one of their strongest performers in all three of those seasons, no matter what weaknesses were elsewhere. He is a reliable, experienced defender who can also pop up with a few goals.