Guptill at least has scraped a few runs at Test level, most against Bangers but he is getting there. In round 17 I'd say Guppy would be a better pick than Nash.
Failed in every series bar the Banga one and his most recent one which hadn't happened when he got picked IIRC
I picked him during his first innings when he was on 30 odd in hope he'd average 100 during the series Fair to say Guptill will be in the NZ setup for awhile as he is a love child so between now and the next cpl in 2 years time he could very well score at an average of 40 he is only 24 and still learning the ropes of test cricket. Despite not knowing the ropes of FC cricket.