but actually Rehhagel deserves massive credit for what he achieved with Greece.
Rehhagel deserves a lot of credit in general. He became a bit of a joke in his latter years and maybe missed the right moment to retire, but it shouldn't diminish his overall achievements and they clearly are fantastic.
His 14 years at Bremen are incredible. He took over in the 2nd Bundesliga, finished the season by getting promoted and never looked back. In the first 8 seasons in the Bundesliga Bremen never finished outside of the top 5. He won 2 league titles, was 4 times runners-up, won 2 cups and the European cup winners' cup.
His one year at Bayern didn't go too well, because Rehhagel was a bit of a difficult character and he couldn't handle the star players, but he still finished 2nd and lead the team to the UEFA cup final (he was fired 3 weeks before the end of the season and Beckenbauer won the final as interim manager).
He then took over in Kaiserslautern in the 2nd Bundesliga, got instantly promoted and won the Bundesliga the following year and finished 5th the following two seasons, which wasn't good enough for the fans who wanted him gone and so he was fired a few weeks into the 2000/01 season.
So he took over the Greek nationalteam, finished top of their Euro qualifying group ahead of Spain and won the tournament.
The fact that he didn't work at the only European top team he ever managed means he's probably a bit underrated in a comparison with all the other great managers of the last 30 years, but he was no doubt a brilliant manager. And some of his teams actually played really attractive football.