The Switzerland international told the People: "The club never believed in me and my years in Dortmund were as hard as you can possibly imagine.
"I went there with so many hopes but, after the first match, a 1-1 draw against Olmutz in the Intertoto Cup, it was over.
"During the break, the coach (Bert van Marwijk) came down on me in the worst possible way and then after the game he added to it in public - he absolutely nailed me against the wall.
"I couldn't believe it. I was just 22 years old, in a foreign country for the first time, at a new club and new league - it just wasn't fair.
"As a result, I was disregarded by everyone - the fans and the media. I was the scapegoat for everything.
"They even blamed me when it rained - they said it was Degen's fault.
"It was an impossible situation. Everybody just waited for my next mistake and Van Marwijk put every obstacle he could find in my way. Of course I made mistakes and did not always play well, I will admit that.
"But, to this day, I cannot explain the totally exaggerated reaction of a football coach."
Degen added: "I am not the only one to suffer this fate.
"Tomas Rosicky went through similar things. He never played to his potential, only for the national team and then when he went on to join Arsenal.
"Liverpool is a new start - the best thing I can think of. I am very proud to play for the club in what is the best league in the world."