Joe is a fantastic shot stopper but he has weaknesses and they are glaring, his bottom left is a spot he struggles to get down to and is constantly beat at when he shouldn't be.
His mind, I hate to say it but he has that English mentality and when left to think he panics, his reactions and instinct saves are from the top drawer though. He has nothing with his feet, absolutely zero but all english keepers have this problem and its the way they were coached. Look how bad Caballero's distribution is and he is far better than Hart.
This is a hunch but I think he's a bit of a shit stirrer in the dressing room, the rumours of the player texting a journalist celebrating Mancini's sacking before the infamous FA Cup loss to Wigan are said to be him and the core of english players we had at the time who were unhappy. Imho Pep is targeting the big presence's in the dressing room who don't fit his mentality and he feels could be disruptive. His interview where he say's Joe can stay and improve or leave almost give off the impression imho he feels Joe doesn't want to learn so off with him. Hart, Nasri, Toure etc.. are all being pushed on for a reason by Pep, the same Pep who has said Delph, Navas etc.. all deserve game time because of how they work in training.
Maybe I'm just reading something thats not there but thats the vibe I get.
As to why people aren't calling it as bad as Mourinho's, I think its the fact Hart, Toure etc... all train with the first team where as Jose has stopped all Schweinsteigers involvement with the first team. Both manager are ruthless and have no room for sentiment, especially with the rebuilding job's both are undertaking.