Very interesting what are they gonna do with him. He's a curious mix of qualities and flaws. Tackling and carrying are his strong points, but these are more extras than something to base your game on at the highest level unless you're some incredible beast that wins the ball back for fun. Hard to believe you can draw these conclusions from Ligue 1. In the bigger leagues, players are more technical and smarter, harder to dispossess.
I'd take tactical IQ, placement, reading of the game, and passing over what he seems to be great at. He is a poor passer (or at least not a gifted one) based on what I'm reading online. How is he supposed to be DM if he is a great carrier of the ball? DMs don't dwell on the ball too much but distribute it to more creative CMs.
And if he is a ball-winner who needs another deep midfielder to organize the game next to him (Something like Lass Diarra with Xabi Alonso), that's a very specific and limited role to have in a team like Real Madrid.