Robbie Neilson admitted he left himself too much to do in the summer after releasing eight players at MK Dons.
The former Dons boss lost his job in January as Dons slipped into the League 1 relegation zone after picking up just two league wins in three months.
Neilson, who helped keep Dons in the division last season, saw the back of the likes of David Martin, Darren Potter, Daniel Powell, Dean Bowditch and Nicky Maynard, but in an interview with STV, admitted he left himself too much to do to replace them and it ultimately cost him his job at Stadium MK.
"Recruitment-wise we had too much of a turnaround," he said. "The results didn't come so the chairman decided he wanted to go down a different avenue. It's part of football.
"I had a great first eight months at MK Dons and the last few months were difficult but you have to have highs and lows in football.
"Ultimately results weren't good enough so you have to take it on the chin as a manager."
The former Scottish international admitted managing at MK Dons offered different challenges to the ones he faces at SPL side Hearts, but said he had no regrets moving south of the border.
He said: "The reason I went down there was not just to progress myself career-wise but as a person as well and I think I definitely did that because it was an eye-opener to say the least at times.
"I think it was an opportunity to go down to England and to a club that could progress and be a project over the next few years. "Having spoken to the chairman there I knew there was great potential in the stadium and the surrounding infrastructure so it was a great opportunity.
"I just felt it was the right club to go to and it was really, really ambitious. It still is. It's had a difficult period in the last three or four years but the infrastructure is there and I just hoped that I would be the one to help them do it.
"I'm 100 per cent a better coach, a better manager and a better coach because you're dealing with things day to day that I didn't have to deal with at Hearts.
"Obviously we didn't have a director of football at Milton Keynes so you then have to deal with different aspects of the whole football club. It was a great learning curve."