Erin Stellato gives us some good life advice:
There are a variety of methods we use for helping customers upgrade to a new SQL Server version, and one question we often get asked is whether or not statistics need to be updated as part of the upgrade process.
tl;dr
Yes. Update statistics after an upgrade. Further, if you’re upgrading to 2012 or higher from an earlier version, you should rebuild your indexes (which will update index statistics, so then you just need to update column statistics).
Make this one of your “Not too long; did read” posts of the day.