Holding is just so clearly not good enough for a club like Arsenal.
I mean, Mustafi at least has the basic abilities for it, he's just to rash and unclever on many ocasions.
Not a hard decision as to whom I'd bin first.
Holding was a victim of early promise and a bad injury, but yeah, we can't just wait around hoping he becomes good enough for us. He'd do very well for a smaller PL team, in an organised and compact system he could be a really good defender.