Matip is criminally underrated and his ability to get on the pitch consistently is at the root of that.
If he was more durable and elected to play for his country of birth - this guy would have 100+ Germany caps and a World Cup winner's medal.
Personally I think the guy is in the Top 10 Centre Halves in the world, if we're accounting for quality and durability isn't a factor.
Good in the air, good at one-on-ones, reasonably mobile, great passer, surprisingly effective dribbler, attacking threat at set-pieces... He's a great player.