In last 25 ODI games he averages 43 including that forgettable England series for him.
Also in those 25 games 12 were won by NZ and he averaged 73 in them.
Ryder meanwhile has average of 39 in his career and 38 in matches won by NZ.
So if Taylor fires NZ is more or less guaranteed victory.
Iirc Taylor had a heap of not-outs against the Windies, that would boost his average by quite a lot. Ryder also has a higher strike-rate.
It doesn't really matter though, Taylor and Ryder are pretty much even. Although what you said is true, when Taylor fires NZ wins a lot more of the time.