Wasn't sure whether I would choose him or Aspas at first, but considering I have an untradeable 87 Aspas, I figured it would be better to go with Casemiro for now, and I couldn't be happier with the decision. Probably the best pure CDM that I have used thus far. I don't really ask him to do much of anything offensively, but that is because he is so good defensively, he allows other players to be more attacking.
Pace: I use a shadow on him which gets him to 77, which isn't great, but isn't terrible either; it's pretty good for a defensive midfielder though. He's certainly quick enough when you tell him to stay back while attacking, like I do, because you're limiting his running, and he is quick enough to make the defensive cover runs that i require of him.
Shooting: Because I tell him to stay back, he doesn't get forward often enough to shoot, plus if he is getting forward, the defender often panics and will charge at him and Casemiro can hit an open player with a pass. On the rare occasions I do shoot with him, it certainly is powerful, albeit not very accurate, even with 85 long shots. A lot of shots go straight at the keeper, which I am okay with because it often has to be parried over for a corner because he strikes the ball so hard.
Passing: I don't ask him to be the creative force in my team, I just use him to make sure the team ticks over; transitioning from defense to attack at whatever speed I want. He plays nice short passes with other midfielders and forwards, and plays beautiful long balls over the top for my wingbacks to run onto. Plays excellent threaded/hard passes forwards when you want to attack quickly and/or get in behind. Combines well with Cbs as well, never putting them in a bad position.
Dribbling: He's alright on the ball, but definitely not the player you want to go on long, winding runs with. Turns well on the ball, particularly when he receives the ball from his CBs, turns tight and quick, and sprays a pass quickly to start the attack. Because he controls the ball relatively well, and is so strong, it is very difficult to push him off the ball.
Defending: An absolute star. Cuts off several passes a game, and when he does get the interception, he controls the ball well enough so he keeps the ball to begin the transition forward. He marks all attackers that make late runs into the box, so my CBs have one less man to worry about. Wins more headers than I would expect a traditional midfielder to win, perhaps thanks to his height. Whether standing or sliding, never misses a tackle. Muscles people off the ball with ease, although this may be a combination of his defending and physicality.
Physicality: Physically elite. Extremely strong to the point not even the likes of Lukaku or Mandzukic (to name the last few I've played against) can bully him. His aggression is intense, as he is constantly fighting for the ball, both in the air and jostling with defenders, and coming away with the ball most often than not. 88 stamina is plenty for A CDM that I tell to stay back. Even if I did give him more license to get forward, it would still be more than enough.
Defending is unparalleled in the midfield
Physical freak, particularly for a midfielder (height, strength, jumping)
Passing/transitioning to attack
Easy, quality links
Crossing (just don't try it, trust me)
A bit slow, particularly on the ball at times
Expensive? (I prebought the players a while back, so it cost me relatively little, but is probably quite expensive now)