People who expect new games In a series to match its predecessors scores are going to be disappointed. Reviewer are much harsher then they used to be and especially so on sequels. Just look at the scores of other new sequels.
Batman AK. Mid 80's even tho it's no worse than Arkham city.
Fallout 4 mid 80's. Black ops 3 has an 81 I believe even tho the consensus(I haven't played it yet) is that it's the best one in years. Look at the witcher 3, it's got a similar score to witcher 2 even tho it's vastly better. Dragon age won game of the year last year even tho it had what a 90. And the same goes for 5. The consensus seams to be that it's better than halo 4(87) and reach(91).
For new games and especially sequels the following is true in my OPPINION.
80 is the new 84-87
85 is the new 89-92
90 is the new 94-97
95 is the new 98+
I won't talk about Halo but just about the reviewers being harsher... that is not true.
And a lot of games shows that... MGS, Tomb Raider, GTA, TLOU, Bloodborne, The Witcher 3, etc...
So I disagree with that until somebody can prove the opposite.