And one of the things we should learn from it that players that fit AM midfield aren't exactly fit for Barca system . may be a young player who can learn like Saul but certainly not a defensive minded player like Augusto at the age of 30
To be fair, Augusto played good in Celta's system which is more similar to ours than Atletico's. He's adaptable and without doubt a good player. But as I said, I don't think he could play Busquets role in our system and he wouldn't add much more offensively than our current CMs, so why buy him? Maybe he'd be a bargain signing for 4M and good squad player, but not someone to cry about that we missed him. If he was around 24 yo he'd be worth to take, but then his price would be most likely much higher.
And he was Atletico's replacement for Tiago, not Arda, so we can't say we should buy Augusto instead of Arda. They are different type of players with Arda being much better of them, he just didn't show all his qualities yet in Barça. I hope he gets another season to do that (if we don't get some really good offer we can't turn down).