Black can not have been attending. 31...Qxa4 would have been quite good enough for the win.

White is winning again.

Good start and efficient finish (helped by Black). Black had his chance. The thing is, no matter how big your advantage, it can be thrown away with just one ill-considered move. But it is worth considering the converse: it is a rare position that, however bleak the prospects, doesn't hold out some possibility of an effective defence.