dpb wrote:
HeyBub wrote:
willshak wrote:
...

Good question and I apologize for the omission.

In all the cases, the fences were cedar or PT pickets, 6' tall with
negligible gaps between the pickets.

Still to many potential variables to answer specifically. One would
guess as another wrote that the metal posts were set in concrete while
the wood weren't and/or were deeper. Another question would be was
the failure mode turnover of the post or did they break off? Age and
amount of rain/water would also be effect as would, potentially, the
wind direction and effective shielding perhaps of one side of the
cleared area vs the other such that despite proximity actual wind
loadings weren't the same...far too many possibilities yet to draw
definitive conclusions.

I agree. Wind direction, streaming neutrinos from the Solar Wind, Voodoo, or
a malevolent foreign deity may be behind the difference. Still, some thirty
of my neighbors' fences built with wooden posts are all in a pile while a
similar number using metal are still standing.