What a $#@!ing stupid argument. Being a WC CB or been WC playing as a WC. Makes absolutely no sense at all. You are saying that no matter where Vidal playes he will put in a WC performance or has in the games where he played LB, Holding mid, CB or AM. I definetly must have been drunk or High as $#@! because I seen him play those positions and I never saw anything remotely WC about it.
I am not sure if my english is that bad or you just dont have any knowledge about football since you cant understand the last argument. As a holding mid your are first and fornemst supposed to cover the defense. If you get out of position or overrun you cant cover the defense. As a regista you have to be able to speed play and dictate the tempo of the game. Vidal cant do that at all.
"He maintained the same WC level when he played in other positions" is different from saying he's a WC CB. He can't be considered a WC CB or a CB in general because he doesn't play there often. The distinction between the two isn't exactly subtle.
Your English is fine, that's not the problem. You said as a regista/holding mid, Vidal was poor and has bad positioning. Those are factually incorrect. Playing as a holding mid isn't something new to Vidal, he played that role since he was young and was always good (was impressive as a DM for Leverkusen before switching to AM). And when he played in the middle for us a couple of times, he was good too. As good as Marchisio is in that role for us now. He has been good there for Bayern as well.
If Vidal play in the defence it would be great for us as I never was relaxed when he did it for us (not that it happened a lot)
He played CB for us twice. First in a back-four. He was decent in that game. The second time, he occupied Bonucci's position in a back-three, and he was amazing in that game. The next day, the papers dubbed him "Beckenbauer."
So, I'm not sure which games of ours with Vidal at CB you've in mind.