Well, I assume that when you are a publisher and developer and acquire publishers and developers there's a lot of redundant work. Two people doing exactly the same in marketing, sales, PR, CM, CS, QA, HR plus in the dev part in engine and tools areas.
For being more productive you merge and coordinate the same teams under a global structure following the same vision, workflow and strategy. But there's redundant fat to cut, so they fire some people.
In addition to this, if the gaming division has been generating loses during a couple decades even after investing dozens of billions in acquisitions I think it's normal that at some point they'll axe it firing underperforming people to reduce costs and replacing them for more promising staff.
I think it's what they should do with Phil Spencer, Aaron Greenberg, Matt Booty and Sarah Bond: they should be fired or at least moved away from the gaming division and replace them with someone very capable and successful in their positions. As they did replacing Matt Booty with Turn 10's Alan Hartman.