Try resting him a couple games to see if this helps or reduce the training to like just exercises, have you changed your formation recently or his playing position?.
x 17 x 5 x 1
Double winners x 5 , Treble x 1 ...Perfect league wins 26/26 x 1 (L8).
Every comment I make on this forum is based on my own experiences and so should be taken as such!.
Try resting him a couple games to see if this helps or reduce the training to like just exercises, have you changed your formation recently or his playing position?.