I decided to complete Fred as I was looking for a new box-to-box CDM for my 4231. After playing 10 games with him, I must admit he is pretty badass.
Defensively, he is only comparable to What If Kante but with 4* 4* and only costing 1/7 of the price. The real game-changer is his ability to push forward due to his works rate. This combined with his dribbling and his passing stats (both also better than WIF Kante's) make him a truly versatile player. I decided to play him RB for a couple of games and can confirm he plays well there too.
Kante like tackling, interceptions, and defensive awareness
Can push forward
Excellent passing, dribbling, and pace
Will most likely get the upgrade and become even more on a beast
Can play RB/LB if you don't mind the height
Needs to be paired up with a taller CDM/CM
While he does get forward, he shoots like a blind man