I don't have any proof that what im suggesting is correct. 
but
one thing i have noticed this season, is that if a player plays 'variable minutes' or 'starter-bench' minutes, his game shape has less chance of going up. 
So for instance, this season ive noticed that, when i play my starters, as starters for 2 games, i get 70-80 'starter' minutes. 
 Likewise with my bench, they get 20-35 'bench minutes' plus if they start the third game, another 40 'starter' minutes which equals 60-75 minutes all up. 
Ive found that the guys that are consistent in their roles, tend to have better game shape. 
So with that player you have, i notice he has played 48, then 20 in the cup for most weeks this season. And then not another game. IMO, i think you need to play him in another game during the week. 3 games. In my opinion, 80 minutes over three games is better than 60 mins over 2 games. 
maybe try that?