It doesn't really change the story. Some time back Activision decided to put together another studio and completed this likely before the buyout concluded or shortly after. Then MS surprise closed Tango et al. The establishment of this studio before the closures has just come to light, but this isn't a case of 'you close some, you open some' as the studio was not opened as part of MS's strategy whereas the closures were. And all the questions as to why MS closed those four studios after saying lots to the contrary still remain.
MS closed three smaller studios, regrouped one, and created one large studio.
From a business perspective, this is what happened.