Sullivan says he thinks they now have a better manager, having appointed former Rangers and Scotland boss Alex McLeish.
"We got what we think is a far better manager who has managed at a high international level," he added.
"You've got to remember, when Steve left we'd lost seven of the last eight games, the only team we'd beat was Wigan.
"Well we managed to get rid of the manager and get three million pounds which was incredibly good business for the club.
"Two more games and the fans would have been screaming for his blood, 'sack the manager, sack the manager.
"Everything we've ever done, I promise you, is for the good of the club, I work morning, noon and night for Birmingham City and we've done a very, very good job."