His stats are amazing, easily one of the best CDMs in the game.
He did very well for me at CDM (Roaming Playmaker Support) - signed for MUFC from Chelsea at start of third season for only GBP 7mil
Don't forget that at DLP Defend he isn't likely to get many assists/key passes nor goals - a very important factor in how the engine gives ratings.
Example: I have Pogba at CM Support - ratings very good but not 8.5 every game. But when I watch extended highlights I see how important he is at winning the ball and building up play. Same with Matic.
Think of a striker who is useless all game getting 6.7, then scores a late tap in goal and ends on 7.8.