But it wasn't my homework. But since you are the mod and you asked for it...Kvally left his homework undone. As I said, you'd have to look at Gamespot's pattern of rating PS exclusives, too, in order to rule out that it wasn't just the fact that Gamespot grades games harder in general (vs. just MS games).
Uncharted 4
Gamespot: 100/100
Metacritic: 93/100
The Last Guardian
Gamespot: 90/100
Metacritic: 82/100
Nioh
Gamespot: 90/100
Metacritic: 88/100
Nier Automata
Gamespot: 90/100
Metacritic: 88/100
Horizon Zero Dawn
Gamespot: 90/100
Metacritic: 89/100
Persona 5
Gamespot: 90/100
Metacritic: 93/100