Griffiths signed for Leeds in January with the intention of earning a place in Australia's World Cup squad, but he was overlooked by Hiddink after making only two sub appearances last season.
Griffiths said in the YEP: "The last six months have been quite tough for me, on and off the field. Without playing any games it was pretty much a coin toss whether I'd make the squad, it cost me a World Cup.
"(Blackwell) tried to play me into a system I wasn't quite used to, a right-wing position and he wanted me to defend. They were crucifying me because they'd paid a transfer for me and I didn't really give them anything."