I get what you're saying and agree teams need those things. Just not sure why you think Arthur has shown he can consistently contribute to the team's success in the ways you have stated.
1) Players work hard.
It's well known he hasn't been at the required fitness levels (even without the injuries).
2) Players react to opponents movements.
I'd say he's good at this but nothing special. Many midfielders are capable of this.
3) Players play based on training sessions.
maybe he does, maybe he doesn't. Not sure.
4) Plays are done according to situations on the field and not names on the shirt.
Every single player who has ever played with Messi has looked for him to do something with the ball and until Messi leaves this will hardly ever change. But again Arthur hardly bucks the trend here.
5) Players respect tactical roles, patterns of movement.
He probably does do this quite well but again not spectacularly well.
If he can stay consistently fit next year then he's a player worth having, if not we would be absolutely mad to keep him if a €40m-€50m offer comes in.
Arthur has sparkles of brilliance. For example, like when he came on vs Bilbao in the Copa recently and made the game's 2 best passes, which let to the only 2, 1 vs 1s chances of the game. Only a very talented player can do that. Or like when he dominated Madrid at his first clasico, and the only way to take the ball from him was to foul him. Or when he came on vs Osasuna and the whole game changed.
But at the moment, these things come only when he is doing extraordinary things. They don't come because of our system, or our tactics, or our movement. They come despite these things. This is what said team values seek to provide. They provide the framework for the player to do these things consistently, without making it seem neither genius, nor particularly risky.
If you don't have proper movement, every progressive pass is a serious risk. And Arthur is a possession player, once he loses the ball it is unlikely he will get it back, with some tackle. With these players, if you have very poor movement & intensity, they will be safety-pass masters. If you have great movement, they will be good-pass masters. He will pull off many many good passes allowing our buildup to take shape and get the ball moving in good positions. He will, from time to time, do some brilliant passes as well (like he's done in some games), but they are not his main role. Their role and value is consistently making good passes and putting decisive players in good positions. For this you need movement, because the area where he plays is crowded with bodies everywhere. To pass in crowded spaces, you need movement and intensity. Sometimes you open space individually, through a dribble, a feint, or something like that, but those are exceptions, something extra. And even in these cases, this is meant to buy you more time, until teammate offer you options for continuation. If said teammates are sleeping on their feet and don't move, it's all for nothing.
About what you wrote.
1) Team is notorious for their bad shape. We are consistently the worse team physically by every parameter almost. So, we already know we are crap physically and we have crap stamina. It's hard not to when there are multiple stories from many sources about our... let's say... very light training and match preparation. Yet, you consider this as something individually related to Arthur. How many games where Arthur didn't even play under Setien where we started intensely, and died off after 40 mins allowing our opponents to pressure us after min 60 simply because we were visibly gassed?
My guess is Arthur looks more tired, than other players. But I see no evidence his stamina is abnormally low in comparison with other players from Barca or even Europe. In CL, where we have data for these things, Arthur's kms per game are well within normal rates. I think he was close to Verratti's numbers.
2) Yea, all players are better at some things and worse at others. It simply means Arthur needs to be very good on the ball to compensate for him being average defensively. We're yet to see how good on the ball he can be under a good system. I think his potential in this area is very high, if we sort the shit out with our team (and I don't mean transfers, but many more).
3) Yes, we don't know. That's my point. We don't know how the bad stuff happening at the team may affect some players.
4) That is not true. Successful Barca team didn't pass the ball to Messi when better teammates were placed.
5) We have very few patterns. When your movement is crap, and you play a possession based model, it means the safety passes going up. Poor movement generate many turnovers for direct styles, and unusually high number of safe-passes for possession based systems. This is not individually tied to one player. Arthur has been missing a good while, and never did our game improved. When Arthur is missing, the team doesn't create more on average.
