Post-closing is the most dangerous time for an information gap.

You just closed the deal. The staff is telling you everything is fine. They are lying. They aren't being indirect because they are mean or duplicitous, but because they are protecting themselves. As the new executive, you have to intentionally break the information bubble. On your first Tuesday, stop the autopsies and run a Pre-Mortem. Declare that, one year from now, the acquisition will have completely failed. Force the legacy directors to show you exactly how the supply chain snaps or where the pixels of a fancy PowerPoint are hiding the real potholes you wish you'd known about. I developed an Executive Survival Guide for exactly this transition. Please DM me if you'd like the verbatim boardroom script I use to foster radical candor in 45 minutes.