He wasn't average at Bilbao. He took over a team that fought against relegation, steadily improved them and finished in 5th place in his second season there. I'd call that pretty impressive. He played brilliant football at Gladbach during the 80's and his first spell at Bayern was pretty impressive as well. He was truely unlucky to go out against Sacchi's Milan side in the European Cup. Don't know much about his time at Benfica and his time at Frankfurt was obviously a disaster, but overall he had a pretty impressive career as a manager, finding and developing some worldclass players and winning quite a few important trophies. He's a two time CL winner, reaching one more final.
That you talk about his second spell at Gladbach, which lasted 6 months, and ignore his first time there when he stayed 8 years in charge and proved himself as a worthy successor of Lattek at Bayern says a lot about how much you know about his career. The comparison to one hit wonder Ranieri is beyond laughable. You could easily argue that he's 3rd best German manager of all time after Lattek and Hitzfeld and we had plenty of excellent ones.
