The 21-year-old defender moved to Germany in the summer after rejecting a new deal at Ibrox.
And the relegated Bundesliga club’s main talent spotter has revealed why they made an unusual swoop into the Scottish market.
Spors said: “I noticed David Bates in my research because he got praise as a very young player in an important match for Rangers against Celtic and his data was impressive.
“He was a player who was obviously under the radar, so we watched the game again and he was really good.
“Then I flew to Glasgow, watched him live and then met him in person. Added to this was a very favourable contract situation.
“Sometimes you can discover players by random and that’s what happened here. There is no one way to find a player.
“With Bates, we were so confidence about the player’s ability, we would have signed him for either the Bundesliga or Bundesliga II - whatever league we were in.
“He has huge potential for development and he has the right mentality to make an immediate impact. We want players like him.”