Four years on, Adler, now at Hamburg, is playing brilliantly and was recently called into the national team for a friendly against old enemy The Netherlands. At 27, his career has progressed to the level many expected back in 2008.
It's just that everything went wrong in between.
The international retirement of Jens Lehmann and the horrifying death of Robert Enke helped primed Adler for the grand stage of the 2010 World Cup, and he began Germany's qualification campaign as the number one. But a serious rib injury which required surgery just a month before the tournament ended his World Cup dream. Little did he know it was only the start of his troubles.
Manuel Neuer excelled in South Africa and became the entrenched number one. Adler's injury was more troublesome than first expected. His return to action was delayed, and when he did come back, he wasn't the same. Explosiveness was replaced by hesitancy. He played as if he didn't trust his body. More injuries followed, including knee surgery. He lost his place at Leverkusen to Bernd Leno, while a new crop of even younger keepers such as Marc-Andre ter Stegen and Ron-Robert Zieler built reputations and forced their way into national team reckoning. Adler was fast on his way to irrelevancy.
At the end of the 2011/12 season, Hamburg signed Adler on a free transfer, and he began the new season as number one. Injuries finally behind him, he immediately began performing at his athletic, spectacular best, buoyed by newfound maturity and the kind of perspective that comes with seeing how easily a career can disintegrate. Germany are blessed, as usual, with a wealth of goalkeeping talent, but it's to Adler's credit that he has inserted himself back into the discussion.
Enjoy some of his work from this season: