Not trying to 'excuse' anything as nothing has been done wrong and the team was managed to a treble so the manager knows his players and that includes Barta.
If he wants to leave that is his choice, personally would rather he stays but up until now he has not done enough to be a starter the onus is on him to change that.
Why would you rather he stay? We already have four CBs who are better than him, right? I remember us discussing this in detail. We still haven't gotten those matching rings, either.
Not every player needs to be a starter. 3rd choice is something that can be strived for, however. Bartra has no real chance of getting that if past seasons are any indication. Mathieu got the nod over him whenever he was healthy more or less by default just by virtue of being the shiny new signing and Vermaelen is likely to be much the same.