That's not quite correct. The law states that "If the boundary results from an overthrow or from the wilful act of a fielder, the runs scored shall be any runs for penalties awarded to either side, and the allowance for the boundary, and the runs completed by the batsmen, together with the run in progress if they had already crossed at the instant of the throw or act."
It's not quite clear what this means. At the time of the the throw, the batsmen had not crossed so it should have been five runs but if "the act" refers to the ball striking the bat, then they had crossed and it should have been six. I think that if I'd been umpire, I'd have given five as it was hard luck on the Kiwis (and Stokes indicated as such) but it was a tough call.
I know umpiring decisions even out but England have had a stroke of luck with umpires in two close games now: Edgbaston 05 (where the umpire definitely got it wrong) and Lord's 19 (where the umpires arguably did). If I were Morgan, I'd be doing the lottery today
