Similar to Semedo he received not regular gametime and been unused in important games, even if he had a good performance before. Hasnt really shown in his games. He has been solid whenever called, waiting for his chance. Now whining about Semedo not playing regulary, while he has played majority of CL games and good portion of La Liga ones is just ridiculous. Hell, Digne has been on average better than Semedo. So are you saying Digne is particulary strong individual to not be affected of being on bench or then you are just bullshitting. He signed for the best club in the world and he cannot take being on bench or competition? If that is the case, he is at wrong club.
Most definitely you have never been a coach or a pro-player, otherwise you wouldn't belittle the importance of several mental factors, like uncertainty, fear, imbalance, frustration, etc.
These are most often more important than the strength of a muscle or even stamina.
Do you really think that the constant "prove yourself" yields and orders by the coach would lead to the required result?
It just gives the opposite result my austere friend...
A player constantly fighting for his place will be uneasy, stiff, frustrated, undecided, he wouldn't take risks, would be afraid of doing creative things, would be scared of dribbling, making creative passes, etc. If he is a defender, he would definitely do more faults, collect yellow cards, etc.
Just ask your sexologist friends, where it is leading to, if the permanent but stiff will to prove yourself becomes a must, when you wish to procreate...
No player can play well or outstandingly if these axes are hanging over his head at every given minute.
You also belittle the role, or mental state of Roberto, he is clearly not happy playing as a defender (specially at important games against strong or even better opponents), so you just provide the ages old prescription, and think that performances - only and always - depend on "waiting for his chances" or someone is "a strong individual to not be affected of being on bench".
Nobody likes to sit on the bench (except Arda Turan) but simultaneously no player deals well with the constant "prove yourself" biddings or arrangements.
Otherwise you also mention valid points, but you're seemingly not aware of the mental factor's importance...
BTW, Digne has NOT been on average better than Semedo, he is probably half as skilled as Semedo is, but you are also damn right in saying that none of us knows how he or someone else is behaving in dressing room, or training.