The Scot controversially moved to Villa Park from Birmingham City in the summer of 20112 but he failed to win over the club's fans and the team narrowly avoided relegation from the Premier League.
However, despite accepting that it was the right time for a change, McLeish insists that he would have enjoyed success this season.
"I understand, given what happened towards the end of last season, that it was difficult for me to stay. But no-one is able to complete a project of that size in 12 months," McLeish told the Daily Mail. "I was confident I knew what was needed. There were big changes in my mind ahead of this season. We needed players. An influx of quality.
"The way it all ended, it was difficult for me to go any further.
"I knew I needed to be out of the job. It had become a mental drain towards the end."
Villa are currently 14th in the Premier League under their new manager, Paul Lambert.