It's not that his stats are buffed, they're just wrong. They make no sense.

He should look more like this:

Level 10-ish
STR 18
Dex 12
Con 16
Int 10
Wis 18
Cha 12
PROFICIENCY BONUS +5
Initiative +3

So, with emphasis on strength, con and wisdom, with weaker dex and intelligence and charisma.