He has been bad this pre-season, yes, but stop overreacting. I don't recall him ever being that bad in official games.
I have wrote a few times, stats from any season.
Bartra almost always plays only against Cordoba and Levante.
Copy/paste from another thread, a post from March, Bartra's matches last Season:
-- 15. Elche
-- 18. Levante
-- 19. Granada
Away:
-- 7. Malaga
-- 11. Rayo
-- 14. Eibar
-- 15. Elche
-- 16. Almeria
-- 17. Deportivo
-- 19. Granada
-- he did play in a few tougher matches like:
-- Champions league (Ajax, Ajax, Apoel, Apoel, Psg home)
-- and all cup matches, plus cup match against Atletico at home
So, you see, he rarely plays against teams that cause us any troubles...
Those teams don't attack too much and he is a beast then and he easily tackles lone strikers from Levante when they come into our half. (1 attacker against 2-3 of our defenders in every duel)
He doesn't get chances against bigger teams.
And when he does, he rushes like yesterday or against Man Utd into every tackle, and he looks like a rookie schoolboy.
He makes at least 3 horrible mistakes all the time, and those mistakes are easier too see against bigger teams than against Levante:
1. he rushes into every tackle, every single time. When he fails in that tackle, he looks like in Januzaj's or in Hazard's goal, all over the place, on the wrong foot, falling to his ass etc. Again, because he rushes, and it is easy to caught him at the wrong feet
If Messi would play against Bartra, with Bartra's rushing, Bartra would probably fall down 3-4 times per match on his ass when he would rush on Messi (and when Messi would make a trick and change a direction)
2. that rushing high up the field, trying to take the ball, and if he doesn't take the ball, he opens a lot of space behind him (if it is around the box, an opponent will shoot on goal. If he rushes up the field, he is allowing them to make an easy counterattack)
3. and again, when we have the ball, he too often tries to create something and runs into the attack or deep in the opponent's half
-- if the opponents take the ball, they can create deadly counterattacks (without an offside) like yesterday a few times
He would need to take some pills to calm down, not to run like a headless chicken for every ball, and to think a little more about WHAT is his position on a field, where should he stay and play all the time, and how much space he is leaving behind his back with those silly mistakes mostly caused by that insane rushing to take every single ball.