In terms of the "normalization" of Germany's party system, I see no reason to dismiss Merkel's relevance in the rise of the AfD - which should be regarded as her most important legacy. Merkel has created a party completely devoid of any sort of coherent ideology and of course committed a cardinal error in August of 2015. That has played a huge role in the rise of the AfD. Of course her supporters are now rewriting the CDU's history in a 1984-like manner, claiming that the CDU has always been a party of the center and not a conservative party at all (that's the sound of Adenauer spinning in his grave you are hearing). It wouldn't have required a right-wing CDU leader to prevent the rise of the AfD, just someone with any sort of discernible center-right ideological preferences. It's quite telling that some of the most glowing tributes to Merkel's time in office have come from the left.
And AKK subscribes to the interpretation of the CDU as a party that essentially does anything to stay in power as well.
True. Just not letting in 1.5 million illegals would have been enough to prevent the rise of the AfD. They were polling at 3% in the summer of 2015 and would've followed the Pirate Party's path to irrelevancy.