Why did Potami lose so much, BTW? You'd have thought Tsipras' acceptance of austerity would have proved them right.
After reading some comments and doing some thinking:
Three effects:
1) sh**tty campaign + uninspired leader - especially debate performance.
2) Losing votes to Pasok, which then lost moderate left wingers to new "responsible" and moderated Syriza (leftwards transfer).
3) Losing votes directly to moderate Syriza.
4) BKs idea that they lost the non-ideological protest vote to Union of Centrists.
My hypothesis is a mix between 1 and 2 were the main factors.