The Dortmund midfielder feels his ability improved during his time in Spain despite his lack of playing time and insists he was right to return to Germany
Injury and form curtailed the Turkey star's career with los Blancos, whom he left on loan in the summer for Liverpool before eventually returning to Signal Iduna Park.
And despite failing to show his best form at Santiago Bernabeu, the Turk believes his game improved during his spell at the club, simply due to the class of players who surrounded him.
"Even in footballing terms, I have learned a lot," he told Kicker. "In retrospect, I can say that my time there took me to new levels.
"One team will reach the [Champions League] final - so my decision with these two teams wasn't so bad!"
Sahin has only made 13 appearances since returning to Jurgen Klopp's side in the winter, but he acknowledges this was always likely to be the case - and insists he made the right decision in returning to Germany.
"It was clear to me that I would not be playing as often as I did in the first title win," he added. "[Sporting manager Michael Zorc and Klopp] have the patience that I don't have sometimes.
"I think my game is as it was before. I don't take any game for granted. Nothing better could have happened for me or my family."