This is a key learning in leadership. Many leaders come in and to make themselves look good, they need to talk about the past in a disingenuous way. This is demoralising for staff who have been part of the journey.
Many years ago I managed a turnaround for an under performing sales team, I made the mistake of trashing the past, three years later I was reminded of how demoralising it was by my peer. I had no idea the impact I had.
With this approach you treating everyone the same, when it may be due to poor leadership, poor culture and any number of factors that the individuals have been subjected to.
Recently tasked with turning around a team, I recalled those important lessons, ensuring the team where recognised and that the transition was no reflection on the team. A critical lesson for taking people on the journey.
With a different perspective I could see the commitment and effort of each member of the team and appreciate their individual contribution. I felt for each and everyone of them, as the situation was not of their making.
Don’t ever trash the past.