... and very likely will never be.
I remember some people saying something like that about Carroll when he was younger.
Well I certainly didn't.
Which is to say that Carroll has always appeared to have the mental toughness required, which was clear in his first few outings in the season we got relegated. Krul hasn't shown that to me. Maybe this is his shaky season, maybe he will improve and make a solid goalkeeper in years to come, but I very much doubt he'll be ready by the start of next season.