The Middlesbrough manager lasted just nine months in the Hoops role because of negative results and 30-year old Hinkel, who retired from the game whilst at Freiburg last year, feels that 'Mogga's' downfall came because he tried to complicate things too much.
"When Tony came in, I thought something big was about to happen. Everything he said to the team was good," Hinkel told SunSport.
"We started the season quite well. We smashed Aberdeen in the first SPL game and we were playing good football but then things slowly changed. The training became different. He stopped the sessions too much.
"Tony had the right intentions. He wanted to do the best he could and make changes to our style but he confused the players by stopping too much. The players didn't know what to do.
"He would stop training and say, 'You need to do this or that better'. He thought about it too much.
"The players just stopped playing the way they could. There was no freedom to their play.
"You also had other coaches giving out different messages and it was very confusing.
"Sometimes you just have to let players play football. Sometimes it's better to be simple.
"Tony wanted to make changes but I felt he over-complicated things at times.
"When Neil Lennon took over, he just let us play. He kept training simple It was maybe two-touch games, but we enjoyed ourselves again."