Well if we're using the median of all parties to calibrate our political spectrum, then GoodSarmatian is wrong, SPD is a center-left party. Same by European standards overall.
I agree they're doing a poor job at it, and feel more like a center-right party. The Union feels like a coalition of "we don't care let's be populist" and "tumbleweeds blowing behind a Merkel cardboard cutout".