Are SoC releases not timed right for Nexus phones?

In the current year 2016, most of the high-end Android phones will ship with the Snapdragon 820 or Exynos 8890 found in the S7/S7 Edge variants. Since the Nexus 6P was a late 2015 release (as usual), was it cost factor or inability to produce in its time frame? (In regards to them opting for a Snapdragon 810).

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